CROJFE - Volume 33, Issue 1 by Studio Bernardic

Editorial – Uvodnik

Looking Forward to the 45th International Symposium FORMEC 2012 Dear readers, I have the honor and pleasure to inform you that the 45th International Symposium FORMEC 2012 will be held in Dubrovnik/Cavtat in hotel Croatia from October 8 to 12 2012 under the title »Concern, Knowledge and Accountability in Today’s Environment«. »FORestry MEChanization« (known under the acronym FORMEC since 1994) is an international scientific network established to investigate and promote the application of mechanization in forest operations and it gathers scientists and experts from Europe and other countries, who, within forestry, deal with wood harvesting, forest accessibility and mechanization of forest operations.

forest accessibility and mechanization of forest operations. Following this idea, the Organizational Committee proposed these topics: Þ Harvesting systems and technologies, Þ Forest road network planning and management, Þ Eco-efficient technologies in forestry, Þ Biomass production and use, Þ Logistics and transport optimization, Þ Forestry and wood industry on close-to-nature principles, Þ Work design and business management in forestry, Þ Ergonomics and work safety in forest operations, Þ IT and remote sensing in forestry, Þ Sustainable forest management and silviculture.

Organizers and main objectives of the Symposium

It was also very important to define the key dates of the Symposium in order to leave enough time to the Organizational Committee to perform well and on time all their tasks (prepare the list of the submitted, accepted or rejected papers, define the schedule of oral or poster presentations, prepare digital proceedings, etc.), and on the other hand to give to the authors (Symposium participants) the schedule of all dates and deadlines associated with them directly or indirectly. Key dates of the Symposium are as follows: Þ Abstract submission deadline: Feb. 29, 2012 Þ Acceptance of abstracts to be made by the Scientific Committee: March 15, 2012 Þ Early registration deadline: May 31, 2012 Þ Full paper submission: July 31, 2012 Þ Registration deadline: Sept. 20, 2012

The main organizers of the 45th International Symposium FORMEC 2012 are the Faculty of Forestry of the University of Zagreb and FORMEC network, while the co-organizers are yet to be defined and until the publishing of this editorial, the agreement has been made with IUFRO (International Union of Forest Research Organizations), Croatian Chamber of Forestry and Wood Technology Engineers, »Croatian Forestry« Ltd. Zagreb, Croatian Forestry Society, Forestry Sciences Academy and CROJFE (Croatian Journal of Forest Engineering). The main objectives and reasons for the organization of this international Symposium are: Þ Presentation of the latest results, up to date achievements and new ideas emerging in the area of forest engineering and in the area of planning forest operations; Þ Promotion of cooperation and exchange of knowledge and experience among forestry scientists, researchers and practitioners.

Topics and key dates of the Symposium When defining and selecting the main topics of the Symposium, the aim was to cover all areas significant for the works related to wood harvesting, Croat. j. for. eng. 33(2012)1

Committees and bodies As a large number of applicants and hence also a large number of participants is expected at the Symposium (more than 200), it was extremely important to gather a team of professionals and hard working people ready to take over the responsibility for the whole organization of the Symposium. Here are the most important committees and their members whom we thank for their engagement and help.

T. Pentek et al.

Looking Forward to the 45th International Symposium FORMEC 2012 (1–3)

Organizational Committee (in alphabetical order): 1. MSc. Ivan I{tok (President of the Committee for Scientific Research of Croatian Forest Ltd.), 2. Prof. Dubravko Horvat (Faculty of Forestry University of Zagreb, Croatia), 3. Assoc. Prof. Vladimir Jambrekovi} (Faculty of Forestry University of Zagreb, Croatia), 4. Prof. Josip Margaleti} (Faculty of Forestry University of Zagreb, Croatia), 5. Assoc. Prof. Tibor Pentek (Faculty of Forestry University of Zagreb, Croatia) – President, 6. Assoc. Prof. Tomislav Por{insky (Faculty of Forestry University of Zagreb, Croatia) – Vice President, 7. Assist. Prof. Mario [por~i} (Faculty of Forestry University of Zagreb, Croatia), 8. Assoc. Prof. Marijan [u{njar (Faculty of Forestry University of Zagreb, Croatia), 9. MSc. Slivija Zec (General Secretary of Croatian Chamber of Forestry and Wood Technology Engineers). Scientific Committee (in alphabetical order): 1. Prof. Antti Asikainen (The Finnish Forest Research Institute, Finland), 2. Prof. Raffaele Cavalli (University of Padua, Italy), 3. Prof. Hans Rudolf Heinimann (Swiss Federal Institute of Technology Zürich, Switzerland), 4. Prof. Tadeusz Moskalik (Warsaw Agricultural University, Poland), 5. Assoc. Prof. Tibor Pentek (Faculty of Forestry University of Zagreb, Croatia), 6. Assoc. Prof. Tomislav Por{insky (Faculty of Forestry University of Zagreb, Croatia), 7. Prof. Karl Stampfer (University of Natural Resources and Life Sciences Vienna, Austria), 8. Assoc. Prof. Rien Visser (University of Canterbury, New Zealand), 9. Prof. Igor Poto~nik (University of Ljubljana, Slovenia. Honorary Committee: 1. Prof. Karl Stampfer (FORMEC President), 2. Prof. Milan Or{ani} (Dean of Faculty of Forestry University of Zagreb), 3. Prof. Hans Rudolf Heinimann (IUFRO Coordinator Division 3), 4. MSc. Damir Felak (President of Croatian Chamber of Forestry and Wood Technology Engineers), 5. Academic Slavko Mati} (President of the Forestry Sciences Academy), 6. Mr. sc. Petar Jurjevi} (President of Croatian Forestry Society).

Schedule of events and further activities of the Organizational Committee In the months to come, the Organizational Committee will develop the network website that should be completed by the end of 2011, and the defined domain of the official network website of FORMEC 2012 will be www.formec2012.hr. All eminent experts, who are directly or indirectly connected with the international scientific FORMEC network, will be contacted through the Symposium first announcements, which will be sent by standard and/or electronic mail. More than 200 participants from the country and abroad are expected to attend the Symposium FORMEC 2012 and more than 90 scientific papers and more than 50 posters from different forestry fields will be presented. At this Conference, after the opening ceremony and plenary session, at which the invitation (introductory) papers will be presented,

Table 1 Program of the international Symposium FORMEC 2012 Time 16:00–19:00 19:00 7:30–9:00 9:00–10:00 10:00–10:30 10:30–12:45 12:45–14:15 14:15–16:15 16:15–16:45 16:45–18:45 20:00 8:00–10:00 10:00–10:30 10:30–12:30 12:30–14:30 14:30–16:30 17:00–19:00 8:00–10:00 10:00–10:30 10:30–12:15 12:15–13:00 13:00–15:00 15:00–19:00 20:00 7:00

Event Event location Monday, Oct. 8, 2012 Symposium registration Reception, hotel lobby Welcome party Tuesday, Oct. 09, 2012 Symposium registration Reception, hotel lobby Opening ceremony Ragusa hall Coffee break Hotel terrace Plenary session Ragusa hall Restaurant Cavtat Lunch Bobara, Orlando and [ipun halls Work in sessions (3) Coffee break Hotel lobby Poster section + discussion Silent salon VIP Dinner Steak House Wednesday, Oct. 10, 2012 Bobara, Orlando and [ipun halls Work in sessions (3) Coffee break Hotel lobby Bobara, Orlando and [ipun halls Work in sessions (3) Lunch Restaurant Cavtat Bobara, Orlando and [ipun halls Work in sessions (3) Field trip 1 (Cavtat or free afternoon) Cavtat Thursday, Oct. 11, 2012 Bobara, Orlando and [ipun halls Work in sessions (3) Coffee break Hotel lobby Plenary session Ragusa hall Conclusions and closing ceremony Ragusa hall Lunch Restaurant Cavtat Field trip 2 (Dubrovnik – Old Town) Dubrovnik Farewell party Restaurant in Dubrovnik (Old Town) Friday, Oct. 12, 2012 Departure of the participants

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Looking Forward to the 45th International Symposium FORMEC 2012 (1â&#x20AC;&#x201C;3)

the activities will be carried out in three, or four sessions (depending on the number of registered and accepted papers). The event schedule will be organized in accordance with the preliminary program. Due to the importance of this Conference for the forestry science and forestry practice, and due to a large number of leading scientists and experts who will present the latest results of their research and

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professional work, most of which is applicable in practice, we would like to thank, in the name of the Organizational Committee and personally, all who have already, or will, make the Symposium FORMEC 2012 still better by their engagement, knowledge or presence. Tibor Pentek, Tomislav Por{insky, Ivica Papa

T. Pentek et al.

Looking Forward to the 45th International Symposium FORMEC 2012 (1â&#x20AC;&#x201C;3)

Croat. j. for. eng. 33(2012)1

Original scientific paper – Izvorni znanstveni rad

Application of a Sugarcane Harvester for Harvesting of Willow Trees Aimed at Short Rotation Forestry: an Experimental Case Study in Japan Takuyuki Yoshioka, Katsuaki Sugiura, Koki Inoue Abstract – Nacrtak An experiment on the growing and harvesting of willow trees aimed at short rotation forestry was conducted in northern Japan. Willows were harvested using a sugarcane harvester from southern Japan during its agricultural off-season. The growing experiment showed the high potential of willow plantations to produce woody biomass of more than 10 dry-t/ha/y. The harvesting experiment showed that space for turning around, one line in one row as a planting method, a growing cycle of three years, and an extractor fan in the harvester are necessary for mechanical harvesting. Mechanical harvesting was considered to have little influence on willow regeneration provided that the machine cut reasonably well-grown trees. The system performance of harvesting and collecting willow billets in a hypothetical model field was calculated as 22.4 m3/h, suggesting the feasibility of supplying low-cost wood chips. Keywords: harvesting, Japan, short rotation forestry, sugarcane harvester, willow

1. Introduction – Uvod Short rotation forestry (SRF), where fast-growing tree species such as eucalypt, poplar, and willow are reforested by planting rooted cuttings and repeatedly harvesting the sprouting stumps in short-term cycles of several years, has mainly been applied for producing pulp chips (Culshaw and Stokes 1995, Hartsough et al. 2000, Stokes and Watson 1991). In recent years, however, SRF has attracted attention worldwide as a new source of woody biofuel. Commercial willow plantations have been cultivated for bioenergy purposes in Sweden since the 1980s, and around 16,000 ha of short rotation willow plantations were established domestically from 1986 to 2000 (Mola-Yudego 2011). Other European countries and North America have been testing harvesting operations using agricultural and forestry machines aimed at SRF (Spinelli and Hartsough 2001, 2006, Spinelli et al. 2007, 2008, 2009, Volk and Luzadis 2009). Similarly in Japan, woody biomass from SRF is defined as an »energy crop« and is considered as a resource in the BioCroat. j. for. eng. 33(2012)1

mass-Nippon Strategy alongside »unused biomass« such as logging residues (Anonymous 2005). This paper outlines an experimental project for growing, harvesting, and utilizing willow trees in Japan. The project is currently underway in the boreal forests of Hokkaido prefecture, northern Japan, and has the following four objectives: (1) bioethanol production from willow tree chips; (2) effective utilization of abandoned agricultural land; (3) soil remediation; and (4) job creation. The growing period of Salix schwerinii and S. sachalinensis, which are indigenous willow species of Hokkaido, is estimated to be three years, and a high annual yield of 10 dry-t/ha/y is expected even with intensive cultivation. A sugarcane harvester from Okinawa prefecture in southern Japan was used for harvesting the willow trees; the machine was shipped a distance of more than 2,000 km to the test site during the agricultural off-season in Okinawa. The usual operation of the sugarcane harvester is as follows: (1) the basecutter cuts the sugarcane at ground level and helps to feed the cane stalks to the

Takuyuki Yoshioka et al.

Application of a Sugarcane Harvester for Harvesting of Willow Trees ... (5–14)

butt lift roller; (2) the butt lift roller lifts the cut sugarcane stalks and guides them into the machine feed rollers; (3) the feed rollers transport and horizontally feed the cane stalks to the chopper drums; (4) the chopper drums cut the sugarcane and send the billets to the extractor chamber; (5) the primary extractor cleans the billets by removing vegetable and mineral impurities; and (6) the removable net container receives the sugarcane billets from the chopper. Regarding the use of a sugarcane harvester for other crops in Japan, Kobayashi et al. (2003) made machine modifications for harvesting kenaf (Hibiscus cannabinus) and examined its performance, and Iwasaki et al. (2007) conducted tests for harvesting wood species. The main purpose of this study was to examine the feasibility of applying a sugarcane harvester to harvest willow trees aimed at SRF. In the growing experiments, growth increments of willows under boreal conditions and cultivation methods to increase the increment were investigated, while methods of land reclamation, planting, and cultivation appropriate for mechanical harvesting were discussed through the harvesting experiments. Operational efficiency and fuel consumption of the harvester were measured, and the influence of mechanical harvesting on willow regeneration by sprouting was evaluated.

2. Material and Methods – Materijal i metode

Three years after planting, which was the growing period in the project, the average annual increment for two years was calculated in the compartment where cut-back was performed, while the average annual increment for three years was calculated in the compartment where cut-back was not performed, and the two increments were compared. As 0.5 × 0.5 m and 1.0 × 0.5 m indicate the spacing between rooted cuttings, the planting density was 40,000 and 20,000 stumps per hectare, respectively.

2.3 Harvesting experiment – Pridobivanje energijskoga drva The experiment was carried out using a crawler-type sugarcane harvester (Fig. 1, UT-100K, Uotani-tekkou, Inc., Japan). Its engine output was 78 kW/ 2,200 rpm and the cubic capacity of its removable net container (Fig. 2) was 2.5 m3. The basecutter of the harvester consisted of two rotary discs with four chopper blades attached to each disc. The machine was used to harvest willow trees in the manner described above, and then was moved to a landing for unloading when the container was filled with willow billets. A time study was conducted during the experiment with the following work elements: moving with no load, cutting, turning around, moving fully-loaded, unloading, hooking up a container, and others. The cutting length of the willow billet was set to 25 cm, and so the harvested willows required secondary chipping in order to be used as fuel for direct combustion equipment such as a boiler.

2.1 Experimental site – Mjesto istra`ivanja The growing experiments were carried out at two sites in northern Hokkaido (NH) and eastern Hokkaido (EH). Three other sites were established for harvesting experiments; two in NH and one in northeastern Hokkaido (NEH), where indigenous willows grow naturally and a site was prepared by leaving rows of willow trees and cutting other ones (see the NEH site in Fig. 3).

2.2 Growing experiment – Uzgojni pokus In order to compare the yields per unit area by performing or not performing cut-back and the difference in planting density (0.5 × 0.5 m and 1.0 × 0.5 m), growing compartments for S. schwerinii and S. sachalinensis were made in the NH and EH sites, i.e., there were 16 compartments in total, and 30 rooted cuttings of five clones were planted in each compartment. Cut-back, which means cutting shoots near the ground after defoliation in the year of plantation, is expected to encourage more shoots to sprout in the following spring and thus increase the productivity of the site.

Fig. 1 Sugarcane harvester Slika 1. Kombajn za {e}ernu trsku Croat. j. for. eng. 33(2012)1

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Table 1 Outline of the three test sites Tablica 1. Opis triju istra`ivanih radili{ta NEH Age, years Dob, godine Number of row Broj redova Length of row, m Du`ina reda, m Space for turning around Prostor za okretanje Planting method (in one row) Metoda sadnje (u jednom redu) Planting density, stumps per 100 m2 Gusto}a sadnje, biljaka po 100 m2 Extractor fan of the harvester Separator na kombajnu

NH Ichi A

Ichi B

Ichi C

Sanru A

Sanru B

3–5

100

Wild-grown Prirodan

No Ne postoji Two lines* Dva reda*

No Ne postoji Two lines** Dva reda**

No Ne postoji Two lines*** Dva reda***

No Ne postoji One line Jedan red

102 ± 25.9

136

100

Running Uklju~en

Non-running Isklju~en

*dense – gusto, **sparse – rijetko, ***staggered – naizmjeni~an

Fuel consumption was measured during the experiment, and the weight of each filled container was measured by truck scale and then converted to dry weight by estimating the water content of the billets. In the experiment, the following elements were examined: operational efficiency and fuel consumption according to the presence or absence of space for turning around, planting method (one line or two

lines in one row), planting density, and running or non-running of an extractor fan. The outline and design of the three test sites are shown in Table 1 and Fig. 3, respectively. There were two sites in NH: Ichi-no-hashi (NH-Ichi) and Sanru (NH-Sanru); three compartments were made at the NH-Ichi site and two at the NH-Sanru site. Due to the wild willows growing in the NEH site, the age of the trees varied (3 to 5 years old, see Table 1) so there were some trees with a diameter at ground level exceeding 10 cm. In addition, since the density of stumps per unit area differed for each row in the NEH site, the influence of planting density on the machine cutting speed was also examined throughout the experiment.

2.4 Investigation on regeneration by sprouting Istra`ivanje vegetativne obnove Willow stumps can be damaged when a sugarcane harvester cuts the trees, leading to concerns about adverse effects on growth in the following year. Tearing of stumps by cutting and regeneration by sprouting were investigated by setting four plots in the NEH site; the length and width of the rows in each plot were 5 m and 2 m, respectively.

3. Results – Rezultati 3.1 Growing experiment – Uzgojni pokus

Fig. 2 Removable net container Slika 2. Odvojivi spremnik Croat. j. for. eng. 33(2012)1

Table 2 lists the results: regardless of planting density, willow species, or test site, the average annual increment of the compartment where cut-back

Takuyuki Yoshioka et al.

Application of a Sugarcane Harvester for Harvesting of Willow Trees ... (5–14)

Fig. 3 Design of the three test sites Slika 3. Nacrt triju istra`ivanih radili{ta Table 2 Results of the growing experiment, dry-t/ha/y Tablica 2. Rezultati uzgojnoga pokusa, tona suhe tvari po hektaru godi{nje Planting density Gusto}a sadnje 0.5 × 0.5 m 1.0 × 0.5 m

Salix schwerinii NH site

EH site

NH site

EH site

0.60

8.84

4.70

10.28

Yes

0.93

11.80

5.06

16.03

No Yes

1.67

9.32

2.89

7.56

3.23

12.11

4.18

9.00

was performed was higher than that where it was not performed. In order to introduce this cut-back practice, however, a method for cutting 20,000 or 40,000 shoots per hectare should be designed. Moreover, since the first harvesting operation itself functions as cut-back, there is no need for cut-back during and after the second growing cycle. Taking cost-effectiveness into consideration, a decision must be made on whether or not to perform cut-back. In terms of planting density, the average annual increment of the sparsely-planted compartment of S. schwerinii was higher than that of the densely-planted one, and vice versa in the case of S. sachalinensis, i.e., the densely-planted compartment produced a higher yield than the sparsely-planted one. Salix sachalinensis and EH showed better results in terms of willow

Salix sachalinensis

Cut back ^epovanje

species and test site, respectively, but some of the data on S. schwerinii in the NH site was significantly low. Since the NH site was located in a water channel area where gravelly soil was predominant, soil fertility might have been very poor in places. However, the overall average annual increment was more than 6 dry-t/ha/y, and more than 10 dry-t/ha/y in the EH site, showing the high potential of willow plantations as woody biomass even in northern Japan.

3.2 Harvesting experiment – Pridobivanje energijskoga drva The results of the time study are shown in Fig. 4, and the relationship between planting density and cutting speed in Fig. 5. The stock of removable net containers prepared for the experiment ran out in Croat. j. for. eng. 33(2012)1

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Table 3 Average operating time of work elements Tablica 3. Prosje~ni utro{ci vremena po radnim sastavnicama Work element Radna sastavnica Turning around (smoothly) Okretanje (bez pote{ko}a) Turning around (with difficulty) Okretanje (s pote{ko}ama) Unloading Istovar Hooking up a container Prikap~anje spremnika

Number Veli~ina uzorka

Avg., sec/cycle Ar. sredina, s/tura

SD, sec/cycle Stan. devijacija, s/tura

26.5

8.45

60.5

17.0

49.7

18.2

93.7

23.9

the NH-Sanru B compartment, so the operation was continued without containers. As a result, the operating times for unloading and hooking up a net container in NH-Sanru B in Fig. 4 are short. The percentage of the operating time for turning around to the total observed time was low in the NEH site, while that in the NH-Ichi and NH-Sanru sites was higher; this difference was due to the presence or absence of space for turning around (see Table 1). The average operating time of the work elements in Table 3 shows that turning around with dif-

ficulty took twice as long as turning around smoothly, suggesting the importance of space for turning around when considering introducing mechanical harvesting. The correlation coefficient between planting density and cutting speed in Fig. 5 is calculated as â&#x20AC;&#x201C;0.246, so there is no clear correlation at the 0.05 significance level. In terms of cutting speed in each test site, NEH (3- to 5-year-old trees) was 28.3 m/min (standard deviation (SD) = 5.25 m/min), NH-Ichi (2-year-old trees) was 41.2 m/min (SD = 11.0 m/min), and NH-Sanru (3-year-old trees) was 36.8 m/min (SD = 6.55 m/min), showing a trend in which the cutting speed decreases roughly in proportion to the tree age (or diameter at ground level). During the experiment, the operator controlled the cutting speed of the harvester since

Fig. 4 Results of the time study Slika 4. Rezultati studija rada i vremena

Fig. 5 Relationship between planting density and cutting speed Slika 5. Odnos izme|u gusto}e sadnje i brzine sje~e

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Application of a Sugarcane Harvester for Harvesting of Willow Trees ... (5–14)

the machine often could not pick up and »swallow« cut willows when the speed was raised. Concerning this cutting loss problem, the machine was found to have difficulty in swallowing willow branches that jutted to the side. Especially in the NH-Ichi site where rooted cuttings were planted with two lines in one row (the width between the two lines was 0.6 m, see Fig. 3), the rows of the willow plantation were wider than the horizontal clearance of the »mouth« of the harvester. Therefore, for mechanical harvesting, one line in one row appears to be a desirable planting method. The operating times for »others« in Fig. 4 were as follows. The operation stopped in the NEH site because four willows, two of which were 9 cm in diameter at cutting height and the other two were >10 cm, were too thick for the machine to cut down. After the experiment, the operator reported that the maximum diameter of willow that the machine could cut down was considered to be 7 cm, suggesting that a growing cycle of three years is appropriate for mechanical harvesting. On the other hand, one of the basecutter blades had to be repaired because the machine »bit« stones in the gravelly soil in the NH-Sanru B compartment. Since the cutting height can be adjusted from the operator’s seat, the height was raised during the experiment in order to avoid breaking the blades. In NH-Sanru B, however, the cutting height of the crawler-type harvester varied due to the rough ground and the machine dug up stones in the soil. Consequently, for harvesting willow trees mechanically, land for cultivation should be reclaimed. Furthermore, a sugarcane harvester is designed to cut sugarcane at 5 cm below ground level, so the basecutter must be improved for application to willow harvesting.

Table 4 lists the fuel consumption and weight of harvested willows per hour and the weight per container (the weight per hour in NH-Sanru B is not calculated due to the shortage of containers, as mentioned above). In the NH-Sanru site, where the running (NH-Sanru A) or non-running (NH-Sanru B) of the extractor fan was examined, there was no difference between the NH-Sanru A and B compartments in terms of fuel consumption. However, the weight of harvested willows per container in NH-Sanru B was less than that in NH-Sanru A; many tops and branches dropped into the net container in NH-Sanru B because the extractor fan stopped during the operation. In view of the importance of gathering wood fiber as well as returning minerals to the soil, the fan should be operated.

3.3 Investigation on regeneration by sprouting Istra`ivanje vegetativne obnove Fig. 6 shows the number of torn and intact stumps and the rate of regeneration by sprouting according to the diameter at cutting height. Although tearing of stumps was observed in every diameter class thicker than 15 mm, all of the torn stumps at the plots sprouted. The rate of regeneration was proportional to the diameter, and all of the stumps with diameters thicker than 30 mm also sprouted. Therefore, provid-

Table 4 Fuel consumption and weight of harvested willows per hour and weight per container Tablica 4. Potro{nja goriva i masa posje~ene vrbe po satu rada te po spremniku Site Radili{te NEH NH-Ichi A NH-Ichi B

Weight of harvested Weight per container, Fuel dry-t/container consumption, willows per hour, dry-t/h L/h Masa posje~ene vrbe, Potro{nja Masa posje~ene vrbe, tona suhe tvari po spremniku goriva, L/h tona suhe tvari po satu 10.05 1.92 0.369 11.12 0.72 0.260 14.54 0.76 0.280

NH-Ichi C

13.51

0.71

0.207

NH-Sanru A

12.00

0.324

NH-Sanru B

12.73

1.26 –

0.260

Fig. 6 The number of torn and intact stumps and the rate of regeneration by sprouting Slika 6. Broj odsje~enih i preostalih stabala te stupanj vegetativne obnove Croat. j. for. eng. 33(2012)1

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ed that reasonably well-grown trees are cut, mechanical harvesting is considered to have little influence on willow regeneration.

4. Discussion – Rasprava Regarding the operational efficiency of the sugarcane harvester, the weight of harvested willows per hour listed in Table 4 is low and unsatisfactory, so machine productivity in a hypothetical model field is discussed. A model field of 270 m in length and 180 m in width is considered here (Fig. 7) and is a typical agricultural compartment in Hokkaido. It is assumed that a sugarcane harvester harvests willows and a forwarder collects removable net containers filled with willow billets. The following assumptions are also made: Þ Four strip roads for the forwarder are set up in the field, and the width of each road is 5 m. Data on the cutting speed in NH-Sanru (36.8 m/min) and the weight of harvested willows per container in NH-Sanru A (0.324 dry-t/container, see Table 4) are used here, while the operating times for turning around smoothly (26.5 sec/cycle), unloading (49.7 sec/cycle), and hooking up a container (93.7 sec/cycle) in Table 3 are also used; Þ The growing stock of willows per hectare at the time of harvesting is 30 dry-t/ha when the growing cycle and the annual increment are three years and 10 dry-t/ha/y, respectively, and the planting area is 4.50 ha (= 180 × 250 m) in consideration of the right-of-way of the four 5-m-wide strip roads. Therefore, the growing stock in the field is calculated as 135 dry-t; Þ The rows of willow trees are spaced at 1.8-m intervals for mechanical harvesting and perpendicular to the strip roads, so there are 100 rows (= 180/1.8) in the field; the growing stock in one row is thus calculated as 1.35 dry-t/row (= 135/100); Þ One cycle of the sugarcane harvester consists of cutting, unloading on a strip road, and hooking up a container. The harvester turns around once every four cycles; Þ Although the weight of harvested willows per container of 0.324 dry-t/container is slightly less than that of the growing stock to be harvested in one cycle (= 1.35/4), the cutting loss during operation is considered; Þ The forwarder collects four containers in one cycle and unloads them alongside a public road on the right side of the model field. The average running distance per cycle is 180 m; the running speed is estimated as 90 m/min, and the operating time for loading and unloading is each estimated as 1 min/container, i.e., 4 min/cycle. Croat. j. for. eng. 33(2012)1

Fig. 7 Hypothetical model field Slika 7. Teorijski model radnoga polja As a result, the operational efficiency of the sugarcane harvester and the system performance in the model field are calculated as follows: Þ In terms of harvesting, the operations of cutting (36.8 m/min, i.e., 101.9 sec/cycle), unloading (49.7 sec/cycle), and hooking up a container (93.7 sec/cycle) are carried out 400 times (98,120 seconds in total), while the operation of turning around (26.5 sec/cycle) is carried out 100 times (2,650 seconds in total). The total operation time is 100,770 seconds, so the operational efficiency of the harvester is calculated as: 0.324 × 400 × (3,600 / 100,770) = 4.63 dry-t/h Þ Considering the running speed of 90 m/min, i.e., avg. 2 min/cycle and the operating times for loading and unloading of 4 min/cycle in each, the one cycle of a forwarder takes 10 minutes, so the operational efficiency of the forwarder is calculated as: 0.324 × 4 × (60 / 10) = 7.78 dry-t/h When the forwarder operates in parallel with the harvester, the system performance is calculated as: 4.63 × 7.78 / (4.63 + 7.78) = 2.90 dry-t/h The system discussed here has the following four advantages: (1) capacity for handling narrow interrows; (2) tracked configuration allowing traversing

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Application of a Sugarcane Harvester for Harvesting of Willow Trees ... (5–14)

of soft or steep terrain; (3) unitization of the product in bags, which allows independent harvesting and extraction, with all related benefits; and (4) better storage quality of billets compared to chips. The average productivity of a sugarcane harvester with the same engine output as the studied one is 6.4 wet-t/h when harvesting sugarcane (from personal communications with an engineer from the machine manufacturer and a researcher from the Okinawa Prefectural Agricultural Research Center). Therefore, considering the water content of willow billets (about 120% on average on a dry-weight basis), it is expected that the performance of the sugarcane harvester in harvesting willows can be as much as that in harvesting sugarcane. The system performance of 2.90 dry-t/h corresponds to 22.4 m3/h of willow billets in volume. In order to discuss willow plantations as SRF, in principle, the cultivation process, e.g., reclamation of land, preparation of rooted cuttings, and application of fertilizer, should be considered in addition to the forwarding and collecting processes. However, a supply of low-cost willow chips could be achieved by introducing large, efficient transporting and chipping machines such as trailers and tub grinders.

5. Conclusions – Zaklju~ci In this study, an experiment on growing and harvesting of willow trees aimed at short rotation forestry was conducted in northern Japan. Willows were harvested using a sugarcane harvester from southern Japan during its agricultural off-season. The following conclusions are drawn: Þ The growing experiment showed the high potential of willow plantations to produce woody biomass of more than 10 dry-t/ha/y; Þ The harvesting experiment showed that space for turning around, one line in one row as a planting method, a growing cycle of three years, and an extractor fan in the harvester are necessary for mechanical harvesting; Þ Mechanical harvesting was considered to have little influence on willow regeneration provided that the machine cut reasonably well-grown trees; Þ The system performance of harvesting and collecting willow billets in a hypothetical model field was calculated as 22.4 m3/h, suggesting the feasibility of supplying low-cost wood chips.

6. References – Literatura Anonymous, 2005: Biomass-Nippon Strategy (provisional translation): Decided at the Cabinet Meeting, Government of Japan, December 27, 2002, Biomass and Bioenergy 29(5): 375–398. Culshaw, D., Stokes, B., 1995: Mechanisation of short rotation forestry. Biomass and Bioenergy 9(1–5): 127–140. Hartsough, B., Spinelli, R., Pottle, S., Klepac, J., 2000: Fiber recovery with chain flail delimbing/debarking and chipping of hybrid poplar. Journal of Forest Engineering 11(2): 59–68. Iwasaki, K., Teraoka, Y., Sueyoshi, T., 2007: Development of woody biomass harvesting system: Cutting characteristics of bishop wood. Journal of the Japanese Society of Agricultural Technology Management 14(2): 81–85. Kobayashi, Y., Otsuka, K., Taniwaki, K., Sugimoto, M., Kobayashi, K., 2003: Development of kenaf harvester and characteristics of the performance. Japanese Journal of Farm Work Research 38(2): 93–98. Mola-Yudego, B., 2011: Trends and productivity improvements from commercial willow plantations in Sweden during the period 1986–2000. Biomass and Bioenergy 35(1): 446–453. Spinelli, R., Hartsough B. R., 2001: Extracting whole short rotation trees with a skidder and a front-end loader. Biomass and Bioenergy 21(6): 425–431. Spinelli, R., Hartsough B. R., 2006: Harvesting SRF poplar for pulpwood: Experience in the Pacific Northwest. Biomass and Bioenergy 30(5): 439–445. Spinelli, R., Cuchet, E., Roux, P., 2007: A new feller-buncher for harvesting energy wood: Results from a European test programme. Biomass and Bioenergy 31(4): 205–210. Spinelli, R., Nati, C., Magagnotti, N., 2008: Harvesting short-rotation poplar plantations for biomass production. Croatian Journal of Forest Engineering 29(2): 129–139. Spinelli, R., Nati, C., Magagnotti, N., 2009: Using modified foragers to harvest short-rotation poplar plantations, Biomass and Bioenergy 33(5):817–821. Stokes, B., Watson, W., 1991: Wood recovery with in-woods flailing and chipping. TAPPI Journal 74(9): 109–113. Volk, T. A., Luzadis, V. A., 2009: Willow biomass production for bioenergy, biofuels, and bioproducts in New York. In: Renewable Energy from Forest Resources in the United States (Solomon, B. D., Luzadis, V. A., eds.), Routledge, London and New York, p. 238–260.

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Sa`etak

Primjena kombajna za {e}ernu trsku pri pridobivanju energijskoga vrbova drva iz kultura kratke ophodnje: pokus u Japanu U radu su prikazani uzgojni postupci, pridobivanje i upotreba energijskoga vrbova drva iz sastojina kratkih ophodnji u sjevernom Japanu. Istraìvane su dvije vrste vrba, Salix schwerinii E. Wolf. i Salix sachalinensis F. Schmidt, koje su autohtone vrste na Hokkaidu. Za sje~u vrbovih stabala kori{ten je kombajn za {e}ernu trsku kako bi se pove}ala njegova iskoristivost izvan sezone ètve {e}erne trske. Uzgojni postupci koji su provedeni u istraìvanju pokazali su da plantaè vrbâ imaju velik potencijal u proizvodnji suhe tvari, i to do 10 tona suhe tvari po hektaru godi{nje, ~ak i uz intenzivnu primjenu uzgojno-tehni~kih mjera. Cilj je ovoga istraìvanja bio ispitati primjenjivost kombajna za {e}ernu trsku pri pridobivanju energijskoga vrbova drva iz sastojina kratkih ophodnji. Pri provo|enju uzgojnih postupaka istraìvan je prirast biljaka pod utjecajem borealne klime, zatim uzgojne metode za pove}anje prirasta, dok su metode za melioraciju tla, sadnju i uzgojni postupci pogodni za upotrebu mehaniziranoga pridobivanja drva raspravljeni u pokusima pridobivanja drva. Uz to su istraìvani u~inkovitost i potro{nja goriva, dok je utjecaj mehaniziranoga pridobivanja energijskoga drva na vegetativnu obnovu sastojina samo procijenjen. Postavljene su dvije pokusne plohe za uzgojne radove na sjevernom dijelu Hokkaida (NH) te dvije na isto~nom dijelu (EH). Plohe su podijeljene u 16 odjeljaka na koje su posa|ene oìljenice 30 razli~itih vrsta klonova. Istraìvani su gusto}a sadnje (0,5 × 0,5 ili 1,0 × 0,5) i utjecaj ~epovanja na proizvodnju drvne tvari. êpovanje je provedeno nakon prve godine. Nakon zavr{etka istraìvanoga razdoblja od tri godine na odjeljcima gdje je provedeno ~epovanje ra~unat je prosje~ni godi{nji prirast za dvije godine, dok je na odjeljcima gdje nije provedeno ~epovanje ra~unat prosje~ni godi{nji prirast za tri godine. Pokusi pridobivanja energijskoga drva provedeni su na dvije pokusne plohe postavljene na sjevernom Hokkaidu (NH), prva je ploha naknadno podijeljena u odjeljke Ich (A, B, C), dok je druga podijeljena na odjeljke Sanru (A, B); uz to je postavljena jedna pokusna ploha na sjeveroisto~nom Hokkaidu (NEH) gdje istraìvane vrbe rastu prirodno (tablica 1, slika 3). Za pridobivanje energijskoga vrbova drva kori{ten je gusjeni~ni kombajn za {e}ernu trsku (slika 3) snage motora 78 kW pri 2200 okretaja. Princip je rada kombajna sljede}i: 1) sje~ivo sije~e trsku/drvo pri tlu; 2) pomo}u sustava valjaka dovodi trsku/drvo do bubnja za sje~enje, koji je prilago|en tako da sije~e komade drva duìne do 25 cm; 3) nakon bubnja za sje~enje isje~ena trska/drvo dolazi u separator gdje se odvajaju biljne i mineralne ne}isto}e (blato, sitne gran~ice koje se izbacuju nazad na proizvodnu povr{inu); 4) nakon separatora komadi trske/drva ulaze u spremnik. Nakon {to se spremnik napuni, kombajn izlazi na pomo}no stovari{te te se zamjenjuje spremnik. Spremnici su vagani pomo}u kamionskih vaga te se na osnovi toga izra~unala suha tvar na osnovi procjene udjela vode u komadima vrbovine. Tijekom istraìvanja proveden je i studij rada i vremena s radnim elementima: kretanje s praznim spremnikom, sje~a, okretanje, kretanje s punim spremnikom, istovar, prikap~anje praznoga spremnika i ostalo. S obzirom na to da je kombajn sjekao komade drva duìne do 25 cm, potreban je dodatni stroj (ivera~) kako bi se dobio proizvod primjeren za upotrebu. U tablici 2 prikazani su rezultati uzgojnih postupaka. Neovisno o gusto}i sadnje, vrsti vrbe ili istraìvanoj plohi, odjeljci gdje je provedeno ~epovanje imali su ve}i prosje~ni godi{nji prirast nego plohe gdje nije provedeno ~epovanje. Ovisno o gusto}i sadnje, plohe na kojima je Salix schwerinii E. Wolf sa|ena rje|im rasporedom sadnice imale su ve}i prirast nego plohe na kojima je sa|ena gu{}e, dok je u slu~aju sadnje Salix sachalinensis F. Schmidt situacija bila obrnuta. Prosje~ni je godi{nji prirast na svim plohama ve}i od 6 tona suhe tvari po hektaru, a na plohi na isto~nom dijelu Hokkaida prirast je ve}i od 10 tona suhe tvari po hektaru godi{nje. Na slici 4 prikazani su rezlutati studija rada i vremena, dok su na slici 5 prikazani rezultati ovisnosti gusto}e sadnje o brzini sje~e. S obzirom na to da je na plohi NH Sanru B postojao nedostatak spremnika, vrijeme za istovar i prikap~anje novoga spremnika je kra}e. Prosje~ni utro{ci vremena radnih sastavnica prikazani su u tablici 3, iz ~ega se moè i{~itati potreba za prostorom za okretanje kombajna. Odnos gusto}e sadnje i brzine sje~e prikazan je na slici 5, za koji je izra~unat koeficijent korelacije – 0,246, {to zna~i da nema povezanosti za razinu zna~ajnosti od 0,05. U slu~aju brzine sje~e primije}eno je kako brzina ovisi o dobi biljaka, odnosno promjeru na panju. U tablici 4 prikazana je potro{nja goriva, masa suhe tvari po satu te masa suhe tvari po spremniku. Na plohama NH Sanru pra}ena je upotreba separatora, u odjeljku A je separator bio uklju~en, dok je u odjeljku B bio isklju~en. Croat. j. for. eng. 33(2012)1

Takuyuki Yoshioka et al.

Application of a Sugarcane Harvester for Harvesting of Willow Trees ... (5–14)

Nije zamije}eno pove}anje potro{nje goriva, ali je uo~eno da su spremnici u odjeljku B imali manju masu zbog neodvajanja sitnih gran~ica pomo}u separatora. U obliku prikupljanja drva, ali i vra}anja dijela hraniva u tlo separator bi trebao biti uklju~en. Na slici 6 prikazan je stupanj vegetativne obnove istra`ivanih ploha nakon provedene mehanizirane sje~e, koji pokazuje da mehanizirana sje~a nema nikakav negativni utjecaj na vegetativnu obnovu vrbovih sastojina kratkih ophodnji. Kako su podaci iz tablice 4 o u~inku kombajna niski i nezadovoljavaju}i, rasprava se temelji na teorijskom radnom polju prikazanom na slici 7, a koje predstavlja tipi~no radno polje na Hokkaidu. Za izra~un modela kori{teni su podaci o brzini sje~e i masi punoga spremnika iz tablice 4, dok su vremena radnih sastavnica preuzeta iz tablice 3. O~ekivana je zaliha na polju nakon ophodnje od 3 godine 135 tona suhe tvari po hektaru ili 1,35 tona u jednom redu, koji su posa|eni na razmaku od 1,8 m. Forvarder u jednom ciklusu skuplja 4 spremnika i istovara ih uz rub javne prometnice, a vrijeme ciklusa je 10 min. Na temelju teorijskoga modela dobivena je proizvodnost kombajna od 4,63 tona suhe tvari po satu, dok je proizvodnost forvardera 7,78 tona suhe tvari po satu. Sustav opisan ovdje posjeduje ~etiri prednosti: 1) mogu}nost rada u malom me|urednom razmaku; 2) gusjeni~ni kombajn omogu}uje rad na nagnutom terenu; 3) mogu}nost pohrane proizvoda u vre}e, {to omogu}uje razdvajanje procesa sje~e i izvo`enja i 4) bolja kakvo}a uskladi{tenih komada vrbe u usporedbi s iverjem. U~inkovitost ovakva na~ina proizvodnje energijskoga drva od 22,4 m3/h upu}uje na mogu}nost pridobivanja velikih koli~ina jeftinoga iverja. Klju~ne rije~i: kulture kratkih ophodnji, vrba, kombajn za {e}ernu trsku, pridobivanje drva, Japan

Authors’ addresses – Adresa autorâ:

Received (Primljeno): December 9, 2011 Accepted (Prihva}eno): January 9, 2012

Assoc. Prof. Takuyuki Yoshioka, PhD. e-mail: yoshioka@brs.nihon-u.ac.jp Assist. Prof. Katsuaki Sugiura, PhD. Prof. Koki Inoue, PhD. Laboratory of Sustainable Forest Utilization Department of Forest Science and Resources College of Bioresource Sciences, Nihon University 1866 Kameino, Fujisawa 252-0880 JAPAN Croat. j. for. eng. 33(2012)1

Original scientific paper – Izvorni znanstveni rad

Mechanized Harvesting of Eucalypt Coppice for Biomass Production Using High Mechanization Level Rodolfo Picchio, Alessandro Sirna, Giulio Sperandio, Raffaello Spina, Stefano Verani Abstract – Nacrtak The main aims of this study were to determine the productivity, profitability and energy balance (output/input) of mechanized harvesting applied to a eucalyptus plantation in central Italy. The study area was located in Rome, at an altitude of 35 m a.s.l., on a flat, even site (average slope gradient 3%). The stand was a eucalypt coppice (Eucalyptus camaldulensis Dehnh.) harvested for the first time in 2000. The planting pattern was square with 3 m among stumps (1111 trees ha–1). By 2009, insect (Phorachantha semipunctata) attacks had reduced stump density to 592 stumps ha–1. The work system applied was the Whole Tree System (WTS) and the final assortement chips for energy. Machine rates were calculated using coefficients and mathematical formulas extracted from the main methodologies proposed by different authors. Energy balance was estimated with the Gross Energy Requirements (GER) method. In these plantations, mechanized harvesting seems most appropriate: this is demonstrated by the high productivity recorded (PSH15 6.5 td.w. h–1 worker–1) and by the favorable energy balance (output/input 23.8, 95.8% system efficiency). However harvesting cost is still high (44.30 € tf.w.–1) and can only be reduced through careful operational planning. Keywords: harvester; work productivity; operating costs; energetic balance; chipper; forwarder; forest plantation

1. Introduction – Uvod In Italy, eucalypt was used mainly for windbreaks and reforestation, especially in the South and in the Islands. Large reforestation programs were launched in 1950s mainly for soil protection purposes in Southern Italy (Calabria and Sicily). Later on, in 1980s new projects were launched for the production of pulpwood (Mughini 2000). Most popular Eucalypt species were E. globulus ssp. bicostata, E. globulus ssp. globulus, E. occidentalis, E x trabutii, E. camaldulensis and E. viminalis. The surface of eucalypt plantations is now estimated at 72,000 hectares (54,000 ha pure, 18,000 ha mixed with other species). Yields vary a lot, depending on species and site. For instance, E. globulus ssp. globules may produce from 10 to 35 m3 ha–1 year–1, whereas E. occidentalis will produce between 3 and 8 m3 ha–1 year–1 (Gemignani 1988). The outlook for eucalypt plantations in Italy can be summarized in three points: Croat. j. for. eng. 33(2012)1

Þ naturalization of less productive plantations, especially in Southern Italy; Þ intensification of crop modules for industrial plantations, in order to increase both the quality and quantity of production (medium rotation coppice and short rotation coppice for wood chips). This will be done using selected clones; Þ rationalized use in agroforestry, where row plantations can offer timber, firewood and wood chips. Energy crops appear as a promising option for ensuring bioenergy feedstock. The profitability of energy crops is highly dependent on appropriate logistics, harvest planning and crop yield (Vega-Nieva et al. 2008). The greatest potential for cost reduction lies in mechanization, which may increase productivity with the introduction of innovative harvesting equipment. Although stand management research regarding the definition of proper practices is now completed, there is always some potential for further

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cost reduction (e.g. refinement of yield-response in relationships for various management practices). Many experimental plots are now entering the coppice stage. In many cases, the primary maintenance practice consists of frequent harvesting that rejuvenates the stand and stimulates fast growth. Traditional practices for harvesting fuel wood are labor intensive, which may discourage maintenance causing the deplorable state of abandonment of many coppice stands in industrialized countries (Spinelli et al. 2006). The main aims of this study were to determine the productivity, profitability and energy balance (output/input) of mechanized harvesting applied to eucalyptus plantation in central Italy. In order to estimate the energy balance, we determined: indirect inputs, i.e. the energy used for equipment production; direct inputs, i.e. fuel and oil consumption; and human energy consumption during work; output, i.e. energetic value of total wood fuel produced. These data were used to determine the economic and energetic sustainability of mechanized harvesting chains. Over these last years, mechanization has been rapidly introduced to forest operations. The Italian harvester and processor fleet now counts over 84 units, and its number doubled in the last five years (Spinelli et al. 2010). Although mechanized harvesting was originally designed and first applied to high forest logging (poplar plantation, coniferous plantation), in recent years it has been employed for harvesting coppice stands. However, the smaller volume of coppice trees implies a lower productivity (Martins et al. 2009). An adequate training of workers and planners is necessary, especially when introducing mechanized harvesting to the sustainable use of forest biomass, as a renewable source of clean energy with reduced greenhouse gases (GHG) emission balance (Picchio et al. 2009). The term »energy analysis« refers to the study of the energy used for the production of a service or a stock. Total energy use includes both the energy directly used during the production process (direct), and the energy stocked in the materials used for the production process (indirect). The Gross Energy Requirements (GER) method is commonly used in energy analyses (IFIAS 1975, Picchio et al. 2009). Although the GER method and the ISO 14040 standard (UNI EN ISO 14040 2006) do not include the assessment of human energy input, man work is of relevant contribution in many production activities, such as forestry activities with low mechanization level. So for a proper comparison between yards with high and low mechanization levels, it will be appropriate to put the human energy input in the energy balance of all forestry yards, even if it represents a low percentage contribution to the total energy inputs. A basic

requirement for any bioenergy generation system is that the energy produced (output) must be greater than the inputs of non-renewable energy required to establish and operate the system (Matthews 2001, Picchio et al. 2009).

2. Materials and methods – Materijal i metode The study was carried out in Rome (41°54'32,55'' N, 12°21'32,34'' E). The study area was characterized by mild climate and volcanic substrata (sand 60%; silt 20%; clay 20%). It had an elevation of 35 m a.s.l. and its terrain was even and flat (average slope gradient 3%, maximum 10%). The stand was a eucalypt coppice (Eucalyptus camaldulensis Dehnh.) (Table 1) harvested for the first time in 2000. The plantation was established in 1989; trees were planted according to 3 m square pattern (1111 trees ha–1). By 2009, insect (Phorachantha semipunctata) attacks had reduced stump density to 592 stumps ha–1. Logging was conducted in summer 2009 on a total area of about 2 ha. All area was surveyed with a Trimble Juno ST GPS device. All operations were carried out by the same private Forest Company. The machines used were: Þ one harvester John Deere (ex Timberjack) 1270 C with a felling-processing head JD (ex TBJ) 762 C, for felling and bunching the trees;

Table 1 Site characteristics Tablica 1. Zna~ajke radili{ta Place – Mjesto Rome (Italy) Surface, ha – Povr{ina, ha 1.72 Slope gradient, % – Nagib terena, % 3 Elevation, m a.s.l. – Nadmorska visina, m n. v. 35 Species – Vrsta drve}a E. camaldulensis Age in years – Dob u godinama 10 Density, stumps/ha – Gusto}a, panjeva/ha 592 Average DBH, cm – Prosje~ni srednji promjer, cm 12.9 Average height, m – Prosje~na visina, m 14.3 Average mass, tf.m. – Prosje~na masa, tf.m. 0.329 Average number of shoot per stump 3.6 Prosje~an broj izbojaka po panju Average mass harvested, tf.m.ha–1 194.768 Prosje~na masa sje~e, tf.m.ha–1 Wood characteristics, chips – Zna~ajke drva, ivera Bulk density, kg m–3 – Gusto}a, kg m–3 320 Moisture content, % – Udio vlage, % 37.59

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Þ one forest loader OP T80, to assist the harvester in tree bunching; Þ one forwarder JD (ex TBJ) 1100 with chipper Erjo for chipping whole trees from bunches; Þ one truck DAF CF 85.430 with trailer VIBERTI 7 LOMASS 22 R for chips transport. There were two forestry operators. The work system applied was the Whole Tree System (WTS). Whole trees were chipped at the stump site, and chips were discharged directly into the transportation vehicles, which could easily access the cutover. The main dendrometric parameters (DBH and tree height) were measured in 2 circular plots randomly selected inside the stand (total surface 5652 m2). A t test for independent samples was applied to each dendrometric parameter and showed no significant difference between the two plots (DBH n° 309, p-value 0.079; height n° 97, p-value 0.647). A tree caliper (Silvanus type 1208, accuracy 0.5 cm) was used for measuring the diameter at breast height (DBH) and a tape logger for determining tree height, after felling. After the harvesting, the height of the felled stump was measured in 2 rectangular plots randomly selected (total surface 1200 m2). A t test showed significant differences between two plots (n° 134, p-value 0.0233). Moisture content and wood density were determined on 30 wood discs (3 cm thick) collected randomly in each plot. The 60 wood discs were immediately weighed with a precision scale (Orma model BC16D) and then taken to the laboratory for determining moisture and wood density, according to the thermo-gravimetric method (UNI EN 13183-1 2003, UNI ISO 3130 1985, UNI ISO 3131 1985, Lo Monaco et al. 2011). Statistical analysis (Kruskal Wallis) showed no significant differences (wood density fresh weight: KW 0.259, p-value 0.611; wood density dry weight KW 0.188, p-value 0.665) between the two plots. For the conversion of volume into fresh mass, we used the measured average density of 1.13 kg dm–3. The top and branches were considered to be the 25% of the stump mass. This figure was determined by weighing the stem, the top and the branches of a sample of 60 shoots, randomly selected on 60 different stumps. The experimental data (felling/bunching and chipping) were recorded for one hectare of plantation. To relate the felling time to tree mass, 110 stumps (396 shoots) were numbered, randomly selected. Slope gradient was measured with a clinometer (Meridian MI 4007). Work time was recorded for every single phase, using a chronometric table Minerva equipped with three centesimal chronometers Croat. j. for. eng. 33(2012)1

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(Anon. 1988, Harstela 1991, Berti et al. 1989, Savelli et al. 2010). In order to calculate outputs in different plots, effective time and delays in the work routine up to 15 min (UT, unavoidable time and AT, avoidable time) (Anon. 1988, Harstela 1991, Picchio et al. 2009) were recorded. Based on work times, volume and mass, the productivity per worker for the different operations was calculated as: average gross productivity (PHS15), measured on the basis of time consumption, inclusive of all delays up to the maximum event duration of 15 minutes; average net productivity (PHS0), computed with the exclusion of delays. The cycle times of the machines were divided into time elements (process steps) that were considered typical of the work. Harvester time consisted of: positioning, beginning when the machine approached the stump and ending when the machine head rested on a tree; felling, beginning when the felling cut started and ending when the tree touched the ground; bunching, beginning when the tree touched the ground and ending when the tree was dropped onto a bunch. Loader time consisted of bunching the tree that the harvester was not able to pile; beginning when the tree was taken from the loader and ending when the tree was put on the pile. Chipping time consisted of: positioning, i.e. the time necessary for the truck to approach the chipper and park by its side; chipping, i.e. the time during which the chipper produced the chips; moving the time necessary for the truck and the chipper to approach a bunch of trees. For all operations, delay was also recorded, i.e. the time during which the machine was not engaged in any productive work process (e.g. repair and/or maintenance, rest, etc.). The influence of tree weight on the felling time was estimated by linear regression, calculated with a regression analysis. Total labor cost (including taxes and all social costs) was 23 € h–1 for the harvester operator and the chipper operator, whereas the loader operator cost was 15 € h–1. Stumpage was 15 € t–1. Fuel cost was assumed at July, 2009. Machine rates (Table 2) were estimated using the coefficients and the mathematical formulas already applied by many authors (Miyata 1980, Picchio et al. 2011a, Spinelli et al. 2011). Further details on cost calculation are reported in Table 2. The energy balance was estimated with the GER method (IFIAS 1975, Picchio et al. 2009). It was used to estimate the direct and indirect input requirements for the machinery used as showed by Picchio et al. 2009. Furthermore, by an indirect method to assess the energy expenditure in forestry operations

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Table 2 Principal calculation elements and machine costs Tablica 2. Glavne sastavnice izra~una i tro{kovi strojeva Description Stavka Purchase price – Nabavna cijena Salvage value* – Preostala vrijednost* Service life – Vrijeme trajanja Annual usage – Godi{nja uporaba Power – Snaga Interest rate – Kamatna stopa Fuel consumption – Potro{nja goriva Lubricant consumption – Potro{nja maziva Garage space – Gara`ni prostor Labor cost – Tro{ak radnika Fuel cost – Tro{ak goriva Lubricant cost – Tro{ak maziva Fixed Costs – Fiksni tro{kovi Variable Costs – Varijabilni tro{kovi Total machine Costs (included labour cost) Ukupni tro{kovi stroja s tro{kom radnika

Unit of measure Mjerna jedinica € € y H kW % l h–1 l h–1 m2 € h–1 € l–1 € l–1 € h–1 € h–1 € h–1

380,000 84,094 10 1,200 173 5 15 0.6 35 23 1.04 9 41.56 66.31

Chipper Eryo on Forwarder (JD 1100) 520,000 115,076 10 800 440(+118) 5 35 1.4 45 23 1.04 9 88.12 114.93

107.87

203.05

JD 1270 c Advance

Loader OP T80 127,000 20,786 12 600 132 5 13 0.52 23 15 1.04 9 24.20 47.57 71.77

(*) The salvage value was calculated by multiplying the purchase price for 0.86N, where N = service life of the machine (*) Vrijednost na kraju vremena kori{tenja izra~unata je uve}avanjem nabavne cijene za 0,86N, gdje je N = vrijeme kori{tenja stroja

in situ (Scott and Christie 2004, Christie 2008) human energy consumption was estimated, on the basis of a human heart-rate response during field work. The two workers were assessed for five work day. Minute-to-minute heart rate was recorded using a Polar heart rate monitor during the test in order to calculate the predicted energy expenditure from working heart rate responses on the basis of individual regression equations. This technique has been validated by several authors (Haskell et al. 1992, Scott and Christie 2004, Strath et al. 2001). To calculate the energy output, the Higher Heating Value (HHV) was determined on 30 chip samples, collected randomly from 10 truck loads (Volpi 1992). Calorimetric tests were conducted with an adiabathic calorimeter (Parr, model 6200) (Canagaratna and Witt 1988). A Kruskal Wallis test suggested limited variability (KW 0.679, p-value 0.712). The average HHV of E. camaldulensis wood was 20.14 MJ kgd.w.–1.

Chipping delays had a very small incidence (9%), much lower than reported in previous bibliography (Spinelli and Visser 2009) (Fig. 2). Moving and po-

3. Results and discussion – Rezultati i rasprava Harvester delays represented 18.1% of the total work time, and in line with the values reported by Spinelli and Visser (2008) for short-rotation plantations (Fig. 1). Harvester delays were mostly due to the need for sharpening the cutting chain; this is explicable considering the type of wood harvested.

Fig. 1 Harvesting and bunching time analysis, percent incidence of time elements Slika 1. Analiza utro{aka vremena sje~e i uhrpavanja, postotni udjeli trajanja sastavnica rada Croat. j. for. eng. 33(2012)1

Mechanized Harvesting of Eucalypt Coppice for Biomass Production ... (15–24)

Fig. 2 Chipping time analysis, percent incidence of time elements Slika 2. Analiza utro{aka vremena iveranja, postotni udjeli trajanja radnih sastavnica sitioning also had a very low incidence, due to the good trafficability of the test area (Fig. 1 and 2). Productivity (PSH15 and PSH0) of each working phase was good (Table 3). As compared to literature data of felling and bunching operations, it had a higher productivity than a harvester used for felling and processing (Spinelli et al. 2002a), but it had a lower productivity and a higher cost than a proper feller-buncher (Spinelli et al. 2002b). The average gross time only for felling and bunching (average stump fresh mass 0.33 tons) was 1.25 minutes, corresponding to a PSH15 per worker of 15.8 fresh t h–1.

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For the regression analysis between dependent variable »gross time (T [min]) for felling and bunching« and independent variable »stump fresh mass (x [t])« 110 stumps were sampled randomly among all the data observed. The regression was expressed by the equation: T = 0.774 + 1.458 x; R2 = 0.678 (Fig. 3). According the regression analysis (Table 4) the model is significant at p<0.001. The elaboration of experimental data collected for chipping, related to the load of 10 trailer trucks, shows a very good productivity: PSH15 of 44.7 t h–1 and a very low level of delay (9.0%), as compared to literature data (Spinelli and Visser 2009, Spinelli and Hartsough 2001). This is mainly due to the good shape of trees and to a good yard organization, but also to the fact that Spinelli and Visser (2009) and Spinelli and Hartsough (2001) included all delay events, including those with the duration longer than 15 minutes. The average calculated height of felled stumps was 11.4 ± 3 cm (p<0.05), a value that indicates the need of lowering the stumps by chainsaw after mechanical harvesting. This is very important for the coppice wood or plantation physiology. Fig. 4 shows the results of financial calculations. The total production cost was 44.30 € t–1, broken down as follows: 14.42 € t–1 for felling, bunching and chipping; 12.83 € t–1 for chip transportation (performed with truck and trailer units, over a distance of about 150 km); 2.05 € t–1 for the relocation and

Table 3 Productivity of felling-bunching (the work of loader included) and chipping Tablica 3. Proizvodnost sje~e i uhrpavanja (uklju~en rad utovariva~a) te iveranja Operation Felling and bunching Sje~a i uhrpavanje Chipping Iveranje Total of the yard Ukupno na radili{tu

PSH15 PSH0 PSH15 PSH0 t h–1worker–1 t h–1worker–1 m3 h–1worker–1 m3 h–1worker–1 15.8

19.3

13.9

17.1

44.7

49.1

39.6

43.5

11.7

13.9

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10.3

12.3

Fig. 3 Variation of gross time only for felling and bunching as a function of the stump fresh mass (from the regression analysis in Tab. 4) Slika 3. Odstupanja ukupnih vremena rada pri sje~i i uhrpavanju kao funkcija mase panja u svje`em stanju (iz regresijske analize u tablici 4) 19

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Table 4 Regression analysis of felling and bunching time predicted for stump fresh mass Tablica 4. Regresijska analiza utro{aka vremena sje~e i uhrpavanja predvi|anih na osnovi mase svje`ega panja Dependent variable Zavisna varijabla min cycle–1 Independent variables Nezavisne varijable Variable Varijabla Stump fresh mass Masa svje`ega panja Intercept Ordinata

0.678

Count Zbroj 108

F-Value F-vrijednost 227.76

p-Value p-vrijednost <0.0001

Unit Jedinica

Parameter Parametar

Std. Error Stand. pogre{ka

p-Value p-vrijednost

1.458

0.0966

<0.0001

0.774

0.0584

<0.0001

transfer of machines; 15 € t–1 for the stumpage (compensation to the forest owner). In this case, the relocation unitary cost was calculated dividing the total cost sustained (2,000 €) for the total surface worked by the yard (5 ha), and the result obtained was divided for the tons of fresh biomass harvested per hectare (195 t). The resulting profit for the enterprise is 5.70 € t–1. The human energy consumption was estimated on the basis of a human heart-rate response during field work. The heart rate was recorded on five work days and the ANOVA test showed no significant differences between the two workers (p<0.05) and between the different operations (p<0.01), and the average value was 87.2 bt min–1 ± 1.3. The calculated ener-

gy expenditure of working was 0.026 MJ min–1 per worker. This value is significantly lower than that reported in other studies (Christie 2008, Picchio et al. 2009, Scott and Christie 2004), but it is clearly explained by the high mechanization used in this yard. Concerning energy inputs, a comparison was conducted between the results of this study and those of similar studies, where the same mechanization level was applied, and in this case it showed similar results (cf. Yoshioka et al. 2005). However, the comparison conducted between the results of this study and others in similar studies, where intermediate mechanization level was applied (Baldini et al. 2007), showed different results. The input for mechanized harvesting was 0.8 GJ td.w.–1 (Table 5) vs. 1.5 GJ td.w.–1 for

Fig. 4 Financial budget of the mechanized forest yard Slika 4. Financijski prora~un mehanizacije radili{ta 20

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Also due to the large amount of biomass harvested, the average output/input ratio was twice as high as the literature data (8.6–11.7, Baldini et al. 2007) available for the harvesting of eucalypt plantations, with intermediate mechanization. Higher values (36–48, Picchio et al. 2009) were also reported, but they were obtained in other forest types (Quercus cerris L. coppice). The percentage energy efficiency (i.e 100*(output – input)/output) was high and on average 95.8% ± 0.3. This value was similar to those reported in other studies (about 91% Baldini et al. 2007, about 97% Picchio et al. 2009).

Table 5 Total energy value of outputs and inputs (GJ ha–1) for all work steps, transport included Tablica 5. Ukupna vrijednost izlazne i ulazne energije (GJ ha–1) za sve sastavnice rada s uklju~enim transportom Output

Machines & Tool Input

Human Input

Total Input

Izlaz

Ulaz strojeva i alata

Ulaz radnika

Ukupni ulaz

0.2

108.1

Direct

Indirect

Neposredni

Posredni

95.2

12.7

2,565.8

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4. Conclusions – Zaklju~ci Mechanized harvesting allowed a substantial increase of the operational productivity recorded for any single work step: felling/bunching, extraction and chipping. Comparison with other two felling studies (Baldini et al. 2007, Martins et al. 2009) reflecting different mechanization levels with escalating investment requirements, confirmed the excellent performance of the harvester John Deere 1270, with a JD 762 C harvester head. However, it had a lower productivity and a higher cost than a proper feller-buncher (Spinelli et al. 2002b) but the harvester was a machine more multipurpose and versatile, and therefore preferred by Italian forestry companies that work in different agroforestry systems. Mechanization resulted in a dramatic reduction of felling costs: moreover, it strongly enhanced operator comfort and safety (Bell 2002). In this kind of plantations, mechanization is most appropriate, as demonstrated by high productivity recorded in our study (PSH15 6.5 td.w. h–1worker–1) and by the very favorable energy balance (output/ input 23.8 and 95.8% system efficiency). These performances far exceed those reported for intermediate mechanization, still very popular in Italy. However, harvesting cost is still high (44.30 € tf.w.–1, Fig. 4) and could be reduced only through careful work planning. The cost of harvesting (6.76 € t–1) would certainly have been lower if it was a proper feller-buncher; the machine has a lower hourly rate and can ensure higher productivity. The unusual use of harvester was

Fig. 5 Percent incidence of work steps on total energy use Slika 5. Postotni udjeli radnih zahvata u ukupnoj energetskoj potro{nji intermediate mechanization. This obviously affects the energy balance (output/input ratio), which is 23.8 for mechanized harvesting and 12.9 for intermediate mechanization. The calculated detail data of energy indirect input requirements for machinery were: harvester 2.37 GJ ha–1 (19%); loader 1.28 GJ ha–1 (10%); forwarder with chipper 2.11 GJ ha–1 (17%); truck with trail 6.94 GJ ha–1 (54%). Fig. 5 shows the incidence of single work phases on total energy input. Truck transport had the highest incidence (45% or 379 MJ td.w.–1), as also found in other studies (Baldini et al. 2007, Picchio et al. 2009), than chipping (33% or 283 MJ td.w.–1) and finally felling and bunching (22% or 185 MJ td.w.–1).

Table 6 Energy efficiency, labor use and operational productivity (PSH15 e PSH0) Tablica 6. Energetska u~inkovitost, korisnost rada i operativna proizvodnost (PSH15 e PSH0) Output/Input Izlaz/ulaz 23.8

System efficiency Man work time U~inkovitost sustava Vrijeme rada radnika % min td.w.–1 95.8 23.12

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PSH15

PSH0

td.w. h–1 worker–1 6.5

m3 h–1 worker–1 10.3

td.w. h–1 worker–1 7.6

m3 h–1 worker–1 12.3

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determined by the fact that the dedicated CTL machine was nearby for the poplar plantation logging. Furthermore, Italian forestry is still confronted with a lack of trained forest workers, which may slow down the transition towards mechanized harvesting. As confirmed by many previous studies (e.g. Baldini et al. 2007, Picchio et al. 2009), this study also shows the urgent need to minimize the costs and energy inputs related to transportation, which can be obtained by developing local markets for energy biomass, thus reducing transportation distance. The cost of chipping was particularly low, due to the power of the machine used and the efficient work system adopted. Field chipping excludes the extraction operation, which often results in long waiting delays for the chipper. The damages to soil and topsoil have not been discussed in this study. The surveys and studies about this yard are still running and they will be the subject of a forthcoming work. In fact, as mentioned by other authors (Picchio et al. 2011), the research on damage caused by forest operations to the remaining trees and/or to the regeneration in forest stands started at the beginning of the twentieth century and its importance has been rising with the increasing use of mechanized wood harvesting.

5. References – Literatura Anon, 1988: Introduction to work study; International Labour Office, Geneva. Baldini, S., Picchio, R., Savelli, S., 2007: Energy analysis of light mechanization yards for the Eucalyptus coppice harvest, Journal of Agricultural Engineering 38(3): 49–56. Bell, J., 2002: Changes in logging injury rates associated with the use of feller-bunchers in West Virginia; J. Safety Res. 33(4): 463–471. Berti, S., Piegai, F., Verani, S., 1989: Manuale di istruzione per il rilievo dei tempi di lavoro e delle produttività nei lavori forestali; Quaderni dell’Istituto di Assestamento e Tecnologia Forestale dell’Università di Firenze, IV, p. 65. Canagaratna, S. G., Witt, J., 1988: Calculation of temperature rise in calorimetry; Journal of chemical education 65(2): 126–129. Christie, C. J., 2008: Relationship between energy intake and expenditure during harvesting tasks; Occupational Ergonomics, 8(1): 1–10. Gemignani, G., 1988: Risultati di un trentennio di sperimentazione sugli eucalitti in Italia. In: Scritti di selvicoltura in onore di Alessandro de Philippis. Istituto di Selvicoltura Firenze/Società Agricola e Forestale (gruppo ENCC) Roma, p. 67–87. Harstela, P., 1991: Work study in forestry; Silva Carelica 18, 1–41.

Haskell, W. L., Yee, M. C., Evans, A., Irby, P. J., 1992: Simultaneous measurement of heart rate and body motion to quantitate physical activity. Medicine and Science in Sports and Exercise 25, 109–115. IFIAS, 1975: Energy Analysis and Economics. Workshop report n°9, Stockholm. Lo Monaco, A., Todaro, L., Sarlatto, M., Spina, R., Calienno, L., Picchio, R., 2011: Effect of moisture on physical parameters of timber from Turkey oak (Quercus cerris L.) coppice in Central Italy. Forestry Studies in China 13(4): 276–284, doi: 10.1007/s11632-013-0405-5. Martins, R. J., Seixas, F., Stape, J. L., 2009: Technical and economical evaluation of a harvester, working under different spacing and planting arrangement conditions in eucalypts plantations. Scientia Forestalis 83: 253–263. Matthews, R. W., 2001: Modelling of energy and carbon budgets of wood fuel coppice systems. Biomass and Bioenergy 21: 1–19. Miyata, E. S., 1980: Determining fixed and operating costs of logging equipment. North Central Forest Experiment Station. USDA Forest Service. General technical report nc-55. Mughini, G, 2000: Eucalyptus breeding in Italy: in International conference »Eucalyptus in the Mediterranean basin: perspectives and new utilization«; CNR-IUFRO. Taormina-Crotone, Italy October p. 15–19. Picchio, R., Maesano, M., Savelli, S., Marchi, E., 2009: Productivity and energy balance in the conversion into high forest system of a Quercus cerris L. coppice in Central Italy. Croatian Journal of Forest Engineering 1: 15–26. Picchio, R., Neri, F., Maesano, M., Savelli, S., Sirna, A., Blasi, S., Baldini, S., Marchi, E., 2011b: Growth effects of thinning damage in a Corsican pine (Pinus laricio Poiret) stand in central Italy. Forest Ecology and Management 262: 237–243. Picchio, R., Spina, R., Maesano, M., Carbone, F., Lo Monaco, A., Marchi, E., 2011a: Stumpage value in the short wood system for the conversion into high forest of a oak coppice. Forestry Studies in China 13(4): 252–262. doi: 10.1007/s11632-013-0411-7. Savelli, S., Cavalli, R., Baldini, S., Picchio, R., 2010: Small scale mechanization of thinning in artificial coniferous plantation. Croatian Journal of Forest Engineering 31(1): 11–21. Scott, P. A., Christie, C. J., 2004: An indirect method to assess the energy expenditure of manual labourers in situ. South African Journal of Science 100, November/December, p. 694–698. Spinelli, R., Hartsough, B., 2001: A survey of Italian chipping operations. Biomass and Bioenergy, 21(6): 433–444. Spinelli, R., Hartsough, B., Owende, P. M. O., Ward, S. M. 2002b: Productivity and cost of mechanized whole-tree harvesting in fast-growing eucalypt stands. Journal of Forest Engineering 2: 49–60. Spinelli, R., Magagnotti, N., Picchi, G. 2010: Deploying Mechanized Cut-to-Length Technology in Italy: Fleet Size, Annual Usage, and Costs. International Journal of Forest Engineering 21: 23–31. Spinelli, R., Magagnotti, N., Sperandio, G., Cielo, P., Verani, S., Zanuttini, R., 2011: Cost and Productivity of HarCroat. j. for. eng. 33(2012)1

Mechanized Harvesting of Eucalypt Coppice for Biomass Production ... (15–24) vesting High-Value Hybrid Poplar Plantations in Italy. Forest Products Journal 61(1): 64–70. Spinelli, R., Nati, C., Magagnotti, N. 2006; Biomass harvesting from Buffer strips in Italy: three options compared. Agroforestry Systems 68: 113–121. Spinelli, R., Owende, P. M. O., Ward, S. M., 2002a: Productivity and cost of CTL harvesting of Eucalyptus globules stand using excavator-based harvesters. Forest products journal 52(1): 67–77. Spinelli, R., Visser, R. J. M., 2008: Analyzing and estimating delays in harvester operations. International Journal of Forest Engineering 19: 35–40. Spinelli, R., Visser, R. J. M., 2009: Analyzing and estimating delays in wood chipping operations. Biomass and Bioenergy 33(3): 429–433. Spinelli, R., Ward, S., Owende, P., 2009: A harvest and transport cost model for Eucalyptus spp. Fast-growing short rotation plantations. Biomass and Bioenergy 33: 1265–1270. Strath, S. J., Bassett, D. R., Swartz, A. M., Thompson, D. L., 2001: Simultaneous heart rate-motion sensor technique to estimate energy expenditure. Medicine and Science in Sports and Exercise 33: 2118–2123.

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UNI EN 13183-1, 2003: Moisture content of a piece of sawn timber. Determination by oven dry method. UNI EN ISO 14040, 2006: Environmental management – Life cycle assessment – Principles and frame work. UNI ISO 3130, 1985: Wood. Determination of moisture content for physical and mechanical tests. UNI ISO 3131, 1985: Wood. Determination of density for physical and mechanical tests. Vega-Nieva, D., Dopazo, R., Ortiz, L., 2008: Reviewing the Potential of Forest Bioenergy Plantations: Woody Energy Crop Plantations Management and Breeding for Increasing Biomass Productivity, World Bioenergy Jönköping, 2008, Sweden May, 27–29. Volpi, R., 1992: Bilanci energetici in agricoltura, »Energy balance in agricolture«. Laruffa Editore, Reggio Calabria, Italy 1992. Yoshioka, T., Aruga, K., Nitami, T., Kobayashi, H., Sakai, H., 2005: Energy and carbon dioxide (CO2) balance of logging residues as alternative energy resources: System analysis based on the method of a life cycle inventory (LCI) analysis. Journal of Forest Research 10(2): 125–134. doi: 10.1007/s10310-004-0126-7.

Sa`etak

Visoko mehanizirano pridobivanje {umske biomase iz eukaliptusovih panja~a Glavni su ciljevi ove studije bili utvr|ivanje proizvodnosti, isplativosti i energetske bilance (izlaz/ulaz) strojne sje~e primijenjene na eukaliptusovim plantaàma u sredi{njoj Italiji. Da bi se procijenila energetska bilanca, odre|eni su: posredni ulazi, tj. energija kori{tena za proizvodnju; neposredni ulazi, tj. potro{nja goriva, maziva i potro{nja energije radnika tijekom posla; izlaz, tj. energetska vrijednost ukupno proizvedenoga drva. Povr{ine pod eukaliptusovim plantaàma danas po procjenama zauzimaju oko 72 000 hektara (54 000 ha ~iste, a 18 000 ha mje{ovite sastojine). Istraìvano je u okolici Rima, na nadmorskoj visini od 35 m, u ravni~nom predjelu (prosje~an je nagib terena 3 %). Sastojina je bila panja~a eukaliptusa (Eukaliptus camaldulensis Dehnh.) posje~ena prvi put 2000. godine. Prostorni je raspored panjeva bio kvadrati~an s 3 m izme|u panjeva (1111 panjeva po hektaru). Od 2009. napadi kukaca (Phorachantha semipunctata) smanjili su gusto}u panjeva na 592 panja po hektaru. Zna~ajke gospodarenja eukaliptusovim plantaàma u Italiji su: Þ povratak autohtonoj {umskoj vegetaciji na podru~jima pod nisko proizvodnim plantaàma, posebno u ju`noj Italiji Þ pobolj{anje sastojina industrijskih plantaà radi pove}anja kakvo}e i koli~ine proizvodnje (sastojine srednjih i kratkih ophodnji namijenjenih proizvodnji drvnoga iverja); navedeno se namjerava posti}i selekcijom klonova Þ racionalizirana uporaba proizvoda u tzv. poljskom {umarstvu (eng. agroforestry), gdje plantaè mogu proizvoditi i tehni~ke drvne sortimente, ogrjevno drvo i drvni iver. Primijenjena je stablovna metoda izradbe i krajnji je proizvod bio drvni iver za energiju. Nasadi za proizvodnju energije dobar su izbor pri osiguravanju sirovine za bioenergane. Isplativost energetskih nasada uvelike je ovisna o odgovaraju}oj logistici, planiranju proizvodnje i prinosa. Tro{kovi strojnoga rada bili su izra~unati pomo}u koeficijenata i matemati~kih formula preuzetih iz vode}ih metodologija koje su predloìli razni autori. Ti su podaci bili upotrijebljeni za odre|ivanje ekonomske i energetske odrìvosti strojne sje~e. Pro{lih godina mehanizacija se brzo uvodila u {umske operacije. Pravilna je izobrazba radnika i planskoga osoblja nu`na, posebno kada se uvodi strojna sje~a za odrìvo kori{tenje {umske biomase kao obnovljivoga izvora energije uz smanjivanje emisije stakleni~kih plinova. Energetska je bilanca bila procijenjena metodom GER (eng. Gross Energy Requirements). Metoda GER tako|er je primijenjena za procjenu neposrednih i posrednih inputa za uoptrijebljene strojeve. Nadalje, kod posredne metode procjene utro{aka energije u {umarskim operacijama u sastojini bila je procijenjena potro{nja energije radnika

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prema otkucajima srca tijekom rada. Dva su radnika bila pra}ena svakoga radnoga dana. Pri dolasku na posao odabrani su radnici bili opremljeni s Polarovim mjera~em otkucaja srca. Za izra~un izlazne energije ve}a ogrjevna vrijednost (HHV) bila je odre|ena na 30 uzoraka drvnoga iverja, koje se skupljalo nasumi~no s 10 kamionskih tovara. Kalorimetri~ni su testovi bili izvedeni s adijabatskim kalorimetrom (Parr, model 6200). Prosje~na vi{a ogrjevna vrijednost eukaliptusa bila je 20,14 MJ kgd.w.–1. Tijekom radnoga vremena prekidi rada harvestera bili su 18,1 % ukupnoga radnoga vremena, prekidi rada pri iveranju zauzimali su manje vrijednosti (9 %), kao i premje{tanje i zauzimanje poloàja zbog dobre kretnosti na istraìvanom podru~ju. U tim je plantaàma strojna sje~a omogu}ila bitno pove}anje operativne proizvodnosti zabiljeène za svaku sastavnicu radnoga procesa: ru{enje/uhrpavanje, izvoènje i iveranje, {to je pokazano visokom zabiljeènom proizvodno{}u (PSH15 = 6,5 td.w.h–1radnik–1) i povoljnom energetskom bilancom (izlaz/ulaz = 23,8; 95,8 % u~inkovitosti sustava). Takva djelotvornost prema{uje onu zabiljeènu kod sustava niè razine mehaniziranosti koji su i dalje vrlo popularni u Italiji. Cijena sje~e (6,76 € t–1) svakako bi bila nià u slu~aju da je kori{ten feler ban~er (eng. feller buncher) koji ima niè tro{kove po satu rada i koji moè osigurati vi{u proizvodnost. Neobi~na uporaba harvestera u tom slu~aju bila je odre|ena ~injenicom da je stroj bio u blizini i da je radio na pridobivanju drva iz topolovih plantaà. U svakom je slu~aju cijena sje~e visoka (44,30 € TF.w.–1) i moè se smanjiti samo pa`ljivim operativnim planiranjem. Prosje~na je visina panjeva bila 11,4 ± 3 cm (p< 0,05), odnosno to je vrijednost koja upu}uje na potrebu dodatnoga skra}ivanja panjeva uporabom motorne pile lan~anice nakon strojne sje~e. To je vrlo va`no za fiziologiju panja~a ili plantaà. Tro{ak je iveranja bio iznimno nizak zbog velike snage kori{tenoga stroja i u~inkovitoga sustava rada. Iveranje u sastojini isklju~uje privla~enje drva, {to ~esto rezultira duìm zastojima pri radu ivera~a. [tete na tlu i na povr{inskom sloju tla nisu detaljno analizirane u ovom radu. Istraìvanje i prou~avanje toga radili{ta i dalje je u tijeku te }e biti predmet budu}ih analiza. Klju~ne rije~i: harvester, proizvodnost rada, operativni tro{kovi, energetska bilanca, ivera~, forvarder, {umske plantaè

Authors’ addresses – Adrese autorâ: Rodolfo Picchio, PhD e-mail: r.picchio@unitus.it Alessandro Sirna, MSc. e-mail: sandrosirna@unitus.it Raffaello Spina, MSc. e-mail: rspina@unitus.it Department of Science and Technology for Agriculture, Forests, Nature and Energy (DAFNE) University of Tuscia Via San Camillo de Lellis, 01100 Viterbo ITALY Giulio Sperandio, MSc. e-mail: giulio.sperandio@entecra.it Agricultural Research Council (CRA) Research Unit for Agricultural Engineering Via della Pascolare, 16, 00016 Monterotondo (Roma) ITALY

Received (Primljeno): November 29, 2010 Accepted (Prihva}eno): November 21, 2011

Stefano Verani, MSc. e-mail: stefano.verani@entecra.it Agricultural Research Council (CRA), Research Unit for Wood Production Outside Forests Periferic Operative Structure of Roma Via Valle della Questione, 27, 00166 Roma ITALY Croat. j. for. eng. 33(2012)1

Original scientific paper – Izvorni znanstveni rad

Productivity and Profitability of Forest Machines in the Harvesting of Normal and Overgrown Willow Plantations Fulvio Di Fulvio, Dan Bergström, Kalvis Kons, Tomas Nordfjell Abstract – Nacrtak Forage harvesters used in Short Rotation Willow Coppice (SRWC) plantations in Sweden suffer from an inability to efficiently harvest stems thicker than 6 – 7 cm at stump height. An alternative, when harvesting in such plantations, might be to use forest machines fitted with accumulating felling heads. This study aimed to measure the time consumption and to compare the costs of two forest machine systems in a normal (N) and an overgrown (O) SRWC, where the respective biomass densities were 36 and 56 Oven-Dry tonnes (OD t) per ha. The first machine system included a harvester and a forwarder and the second consisted of a harwarder (one-machine system). When harvesting and forwarding the biomass for 250 m, the productivity of the two and one-machine system was on average 2.3 (sd = 0.6) and 0.9 (sd = 0.2) OD t/Productive Work hour, respectively. Biomass density or stem sizes had a marginal effect on the time consumption per hectare for the two-machine system, but were significant for the one-machine system. The productivity for the two-machine and one-machine system in the O area, compared to the N area, was 40% and 36% higher, respectively. The net income was positive when using the harvester–forwarder system but it was negative for the harwarder. Increases in biomass density or stem sizes increased the profitability of the machine systems studied. Thus, if dealing with more overgrown plantations than those studied, forest machines, and especially a harvester-forwarder system, may offer an efficient and economical alternative to conventional forage harvesters. Keywords: System analysis, time study, productivity, harvester, forwarder, harwarder

1. Introduction – Uvod Current field design of Short Rotation Willow Coppice (SRWC) plantations for energy has increased the efficiency of cultural operations, allowing for fully-mechanized cultivation and harvesting (Mola-Yudego 2011, Mitchell et al. 1999). The harvesting operation accounts for about half the total cost of SRWC production; the remainder of the cost is attributable to cultivation (25%) and biomass transportation (25%) (Sims 2002). Nearly all SRWC in Sweden are harvested by direct chipping, using forage harvesters equipped with wood cutting headers and shuttles for transporting the chipped biomass to the road side (Nordh and Dimitriou 2003). The forage harvesters tend to have problems with stems and therefore the diameter at stump height (dsh) (i.e. the cutting height) exceeds 6 – 7 cm. For instance, as Croat. j. for. eng. 33(2012)1

such thick stems are relatively inflexible, they are not readily bent to fit into and pass through the feeding and cutting unit (Nordh and Dimitriou 2003). Spinelli et al. (2008) found that when the average dsh exceeded ca. 4 cm, the mechanical stress on the machines increased and in turn reduced the machines’ work availability from 94% to 84% (Spinelli et al. 2008). It is to be expected that future SRWC plantations will achieve higher biomass yields due to the breeding of new and better clones (Mola-Yudego 2011). As such, it is likely that the average dsh of the harvested trees will increase, requiring harvesters that can handle larger stems (Nordh and Dimitriou 2003). In fact, such a need already exists to some extent: the use of conventional forage harvesters can be challenging when harvesting SRWC that has become somewhat overgrown (i.e. which contains a notable amount of stems larger than 4 cm in dsh) (Magnusson 2009).

Fulvio Di Fulvio et al.

Productivity and Profitability of Forest Machines in the Harvesting ... (25–37)

One possible way to work around these problems would be to use forest machines developed for harvesting small trees for bioenergy in first thinnings. Such forest machine systems are highly reliable and can handle stems/trees much larger than those found in overgrown SRWC plantations. In the Nordic countries, two-machine systems consisting of a harvester equipped with an accumulating felling head (AFH) and a forwarder that transports the biomass to the roadside are commonly used for such operations. However, one-machine systems are also used consisting of a machine (a harwarder) that both fells and transports the biomass to the roadside (cf. Talbot et al. 2003). A detailed understanding of the factors affecting the productivity and operating costs of forest machines when used in SRWC plantations could facilitate the development of approaches that would make their use more profitable than that of conventional forage harvesting systems when harvesting significantly overgrown SWRC plantations. Therefore the aim of this study was: Þ to study the effect of work methods and biomass density (normal and overgrown) on the work time consumption of a harvester–forwarder system and a harwarder system in willow plantations, Þ to compare their productivity, costs and profitability.

2. Material and Methods – Materijal i metode The study site was located in Ransta, Sweden (59°49'N, 16°38'E). A Salix viminalis L. clone »Tora« plantation was established there in the year 2000 in a double row pattern (Fig. 2). The plantation was intended to be harvested every five years on a regular basis. At the time the study was conducted, it had been grown by six years since it had last been harvested. The plantation covered an area of 17.2 ha, of which 3.6 ha were used for the study. The study was conducted in 2010, between the 29th of November and the 9th of December. The ground surface was partially frozen and covered with a snow layer to a depth of ca. 5 cm and had a high bearing capacity. The study area was inventoried in rectangular plots with a width of 5 single rows (5 m) and a length of 4 stools (2.4 m) (i.e. a stool is a stump from which stems sprout), giving a sample area of 12 m2. The plots were regularly distributed in the direction of the rows and separated from one another by 10 m, giving a density of 80 plots per hectare. The study area contained both normal (N) and overgrown (O) areas (Table 1). The biomasses were estimated by

Table 1 Average values for the properties of the two study areas. Standard deviations are quoted in parentheses. OD = oven-dry Tablica 1. Prosje~ne vrijednosti zna~ajki dvaju istra`ivanih podru~ja. Standardna je devijacija navedena u zagradama. OD = suha tvar

Properties – Svojstva Density, stool/ha – Gusto}a, panj/ha Density, stems/stool Gusto}a, stabljika/ha Diameter at stump height, cm* Promjer na panja, cm* Height, m* – Visina, m* Biomass, OD t/ha – Biomasa, OD t/ha Biomass, raw mass, t/ha Biomasa, sirova masa, t/ha Mean annual increment, OD t/ha, year Srednji godi{nji prirast, OD t/ha, godina

Study areas Istra`ivano podru~je Normal Overgrown Normalno Preraslo 13,815 (1,527) 12,765 (2,859) 3.5 (0.5)

3.7 (0.7)

2.7 (1.2)

3.1 (1.5)

5.4 (2.1) 36 (8)

6.0 (2.2) 56 (17)

72 (16)

114 (35)

6.0

9.3

*Arithmetic mean value – Aritmeti~ka srednja vrijednost

sampling 35 stems representing the full range of observed dsh; their dsh, height and fresh weight were measured. A sub sample of stems was then chopped into ca. 0.2 liters small pieces and their moisture content (MC, wet basis) was determined according to CEN/TS 14774-2 (2004). The MC was on average 50.4% (sd 1.6%). The oven-dry (OD) masses of stems with different dsh were then used to generate a biomass function [1] (cf. Verwijst and Telenius 1999): Stem mass (OD kg) = 0.0001 ´ dsh2.603; R2 = 0.979 (1) Where: dsh diameter at stump height, mm A harvester and forwarder system and a harwarder system were studied. The harvester was a Valmet 911.1 (Komatsu Forest AB, Sweden) with 4 wheels, a mass of 15.2 t, a power output of 129 kW and a width of 2.7 m. The harvester crane was a Cranab CRH 16 (Cranab AB, Sweden) with a maximum reach of 9.8 m and equipped with the Bracke C16.a (Bracke Forest AB, Sweden) AFH with a mass of 500 kg which cuts trees with a saw-chain attached to a rotating disc with a diameter of 795 mm. The forwarder was a Timberjack 1210B Pendo (John Deere Forestry Oy, Finland) with 8 wheels, a mass of 15.5 t, a power output of 114 kW and a width of 2.8 m. The load capacity of the machine was 14 t and the load bunk cross sectional area was 4.2 m2. The forwarder crane was a Loglift F71 FT (Loglift Jonsered AB, Sweden) with a maximum reach of 10.0 m. The forwarder was Croat. j. for. eng. 33(2012)1

Productivity and Profitability of Forest Machines in the Harvesting ... (25–37)

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Fig. 1 The number of stems (bars) and the biomass (polygons) per ha as a function of stem diameter at stump height for the normal (N) and overgrown (O) areas. Dsh = diameter at stump height, OD = oven-dry Slika 1. Broj stabljika (stupci) i biomasa (poligoni) po hektaru kao funkcija promjera stabala na visini panja za normalno (N) i preraslo (O) podru~je. Dsh = promjer na visini panja, OD = suha tvar equipped with a slash grapple (Hultdins AB, Sweden) with a grapple-area of 0.36 m2. The same forwarder was also used as a harwarder, and in this case it was equipped with the Naarva Grip 1500-25 E (Pentin Paja Oy, Finland) accumulating felling-grapple. During the experiments the harvester, forwarder and harwarder were operated by one, two and one operator, respectively. All operators were professionals and experienced with harvesting of small trees in thinning operations. The harvester felling and bunching work was studied as a function of 3 factors, giving 8 different treatment combinations: factor a, biomass density (N and O); factor b, number of harvested double-rows (5 and 6 rows); and factor g, working method (i.e. front and side to side; see Fig. 2 for an explanation of these terms). The cut stems were bunched in piles positioned to the rear of the machine, at an angle of ca. 45° to the strip road, on the side of the harvester with the butt ends pointing towards the machine (Fig. 2). For each treatment combination the harvester’s operation was studied for at least 0.5 Productive Work hours (PW) hours (IUFRO 1995) and for at most 1 PW-hour, short delays were also recorded. A randomized block design with 3 blocks was used; in total, 24 study units were harvested in the experiment (12 in N and 12 in O) (Fig. 3). The results of the experiment were analyzed by ANOVA, using a general linear model of the form: Croat. j. for. eng. 33(2012)1

yijkl = m + ai + bj + gk + c1 + ai ´ bk + ai ´ gk + bj ´ gk + ai ´ bj ´ gk + eijkl (2) Where: m a b g e

overall mean, biomass density, number of harvested double-rows, working method, error.

The forwarder loaded the piles into the bunk area until a full load was achieved (up to the full length of the stakes) and then hauled the biomass to roadside, where the stems were unloaded perpendicular to the direction of the road, with their butt ends pointing towards the road. The forwarder’s work time consumption was analyzed in terms of the factors a and b (see above) using a linear ANOVA model of the form: yijk = m + ai + bj + ck + ai ´ bj + eijk

(3)

The harwarder cut and directly loaded the stems until the bunk area was loaded to the capacity and then hauled the biomass to the roadside for unloading (Fig. 4). Each load corresponded to a study unit. Six study units (three blocks) were harvested in the O area and two in the N area (one block) (Fig. 3). The results of the work in the O stand were analyzed using a two-way ANOVA model:

Fulvio Di Fulvio et al.

yij = m + ti + bj + eij Where: m overall mean, ti treatment main effect (number of harvested rows),

Productivity and Profitability of Forest Machines in the Harvesting ... (25–37)

(4)

bj eij

block main effect, random error term.

The average work time consumption in the O area (six study units) was compared to the average work time consumption in the N area (two study

Fig. 2 The working methods used with the harvester when harvesting either 5(a) or 6(b) double-rows, in a direction parallel (a.1 and b.1) or perpendicular (a.2. and b.2) to the orientation of the machine. The large hollow arrows on the right hand side of the drawings indicate the machine’s working direction. The alphabetic sequence of capital letters in each drawing shows the sequence of crane cycles (i.e. the stools in the area marked »A« were felled first, then those in the area marked »B«, etc.) The small black arrows in the drawings indicate the direction of the crane’s movement during felling and bunching; the shaded oval regions denote approximately the area felled during each crane cycle Slika 2. Metode rada primijenjene pri radu harvestera kod sje~e 5(a) ili 6(b) duplih redova, u paralelnom ili okomitom smjeru u odnosu na orijentaciju stroja. Velike prazne strelice na desnoj strani crteà prikazuju radni smjer stroja. Abecedni slijed velikih slova na svakom crteù prikazuje slijed ciklusa krana (panjevi na povr{ini A sje~eni su prvi, zatim oni na povr{ini B itd.). Male crne strelice na crteù pokazuju smjer kretanja krana tijekom sje~e i vezanja snopova; zasjen~ena ovalna podru~ja prikazuju pribli`no povr{ine koje su sje~ene u svakom ciklusu krana 28

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Productivity and Profitability of Forest Machines in the Harvesting ... (25–37)

Fig.3 The spatial layout of the study units (cells), with their treatments, in the study area. The italic letter in each of the cells indicates the block affiliation (i.e. »a, b, c« for the harvester–forwarder and »d, e, f, g« for the harwarder). The capital letters indicate the biomass density (i.e. normal (N) and overgrown (O)). Numbers indicate the number of harvested double-rows (i.e. 5 and 6 rows and 2 and 3 rows). The letter positioned after the numbers indicates the harvester’s working method (i.e. in front (f) and side to side (s)) Slika 3. Prostorni raspored istra`ivanih jedinica (polja), s njihovim postupcima, u istra`ivanom podru~ju. Kurzivno slovo u svakom polju prikazuje pripadnost bloka (npr. »a, b, c« za forvarder–harvester i »d, e, f, g« za harvarder). Velika slova pokazuju gusto}u biomase (npr. normalno (N) i preraslo (O)). Brojevi pokazuju broj posje~enih duplih redova (npr. 5. i 6. red te 2. i 3. red). Slova iza brojeva pokazuju radnu metodu harvestera (npr. ispred (f) i sa strane na stranu (s)) units). The data were analysed using Tukey's t-test; differences were considered significant if p < 0.05. The work time consumption was recorded by using the Allegro Field PC® and the SDI software

Fulvio Di Fulvio et al.

(Haglöf, AB). The individual work elements involved in the operation of the harvester took relatively short time and where therefore studied with frequency measurements (cf. Harstela 1991). The harvester’s operational state (i.e. the work element currently in progress) was recorded once every 7 s, giving precedence to the element with the highest priority as specified in Table 2. In addition, the total time consumption was recorded in order to control for missed observations. The individual work elements in the operation of the forwarder and harwarder took a relatively long time and they were therefore studied with snap-back timing (continuous time recording) rather than frequency registration (cf. Harstela 1991). The times were recorded in cmin (i.e. 1 cmin = 1/100 min). The work time was recorded separately for the various work elements listed in Table 3. The harvested area was subsequently inventoried in 28 rectangular sample plots (sized to contain 20 stools) and systematically laid out and spaced 30 m along the strip roads. In each plot, the cutting height of each stool was measured, the number of damaged stumps was counted and the depth of the tire tracks (i.e. the distance between the bottom and the rim edge for each track section) in relation to the midsection of each sample plot was measured. A stump was considered to be damaged if more than half of its radius was cracked.

Fig. 4 The working methods used with the harwarder when harvesting either 3 (c.1) or 2 (c.2) double-rows. The large hollow arrows on the right hand side of the drawings indicate the machine’s working direction. The alphabetic sequence of capital letters in each drawing shows the sequence of crane cycles (i.e. stools in the area marked »A« were felled first, then those in the area marked »B«, etc.). The small black arrows indicate the direction of the crane’s movement during felling and bunching; the shaded oval regions denote approximately the area felled during each crane cycle Slika 4. Metode primijenjene pri radu harvardera kod sje~e 3 (c.1) ili 2 (c.2) duplih redova. Velike prazne strelice na desnoj strani crteà prikazuju radni smjer stroja. Abecedni slijed velikih slova na svakom crteù prikazuje slijed ciklusa krana (panjevi na povr{ini A sje~eni su prvi, zatim oni na povr{ini B itd.). Male crne strelice na crteù pokazuju smjer kretanja krana tijekom sje~e i vezanja snopova; zasjen~ena ovalna podru~ja prikazuju pribli`no povr{ine koje su sje~ene u svakom ciklusu krana Croat. j. for. eng. 33(2012)1

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Productivity and Profitability of Forest Machines in the Harvesting ... (25–37)

Table 2 Definitions of the work elements in the operation of the harvester Tablica 2. Definicije radnih elemenata u radu harvestera Work element Radni element

Description Opis

Priority* Prioritet*

Boom out Prazan kran

Starts when an empty crane moves towards the first stool to be harvested and stops when the first tree has been reached Po~inje kada prazni kran kre}e prema prvomu panju gdje }e se sje}i i zavr{ava kada se dosegne prvo stablo

Felling and accumulating Sje~a i kumuliranje

Starts when the first tree has been reached and stops when the last tree has been felled Po~inje kada se dosegne prvo stablo i zavr{ava kada se zadnje stablo posije~e

Boom in Puni kran

Starts when the last tree in the crane cycle has been felled and stops when trees have been dropped on the ground (includes time spent arranging the bunch) – Po~inje kada je zadnje stablo u ciklusu krana posje~eno i zavr{ava kada su stabla spu{tena na tlo (uklju~uje vrijeme ure|enja sve`nja)

Moving Kretanje

Starts when the machine wheels begin turning and stops when the wheels stop Po~inje kada se kota~i stroja po~inju okretati i zavr{ava kada se kota~i zaustave

Miscellaneous Razno

Other activities e.g. cutting roots away from the bottom of the stems Ostale aktivnosti, npr. rezanje korijena sa stabla

Delays Zastoji

E.g. repairs and personal breaks Npr. popravci i osobni odmori

*If work elements were performed simultaneously, the element with the highest priority (lowest number) was recorded *Ako su radni elementi izvo|eni istodobno, element je s vi{im prioritetom (manji broj) zabilje`en

Table 3 Definitions of the work elements in the operation of the forwarder (F) and harwarder (H) Tablica 3. Definicije radnih elemenata u radu forvardera (F) i harvardera (H) Work element Radni element Boom out, H Prazan kran, H

Description Opis

Priority* Prioritet*

Starts when an empty crane moves towards the first stool to be harvested and stops when the first tree has been reached Po~inje kada prazni kran kre}e prema prvom panju gdje }e se sje}i i zavr{ava kada se dosegne prvo stablo

Felling and accumulating, H Starts when the first tree has been reached and stops when the last tree has been felled Sje~a i kumuliranje, H Po~inje kada se dosegne prvo stablo i zavr{ava kada se zadnje stablo posije~e

Loading, H Utovar, H

Starts immediately after the felling of the last tree in the crane cycle and stops when the bunch of trees has been transferred to the log bunk Po~inje odmah nakon sje~e zadnjega stabla u ciklusu krana i zavr{ava kada je sve`anj stabala prenesen u utovarni prostor

Loading, F Utovar, F

Starts when the empty crane move from its base position in the bunk area and stops when the crane returns to the load bunk Po~inje kada prazan kran krene sa svoje osnovne pozicije u podru~ju le`i{ta i zavr{ava kada se vrati u utovarni prostor

Moving while loading, F–H Starts when the machine wheels begin turning and ends when the wheels stop moving to allow cutting/loading Kretanje pri utovaru, F–H Po~inje kada se kota~i stroja po~inju okretati i zavr{ava kada se kota~i zaustave da omogu}e sje~u/utovar

Moving loaded, F–H Puna vo`nja, F–H

Starts when the machine moves from the study unit and ends when the machine stops at the landing Po~inje kada stroj kre}e s istra`ivane jedinice i zavr{ava kada se zaustavlja na stovari{tu

Unloading, F–H Istovar, F–H

Starts when the machine stops at the landing and ends when the base machine starts to move from the landing Po~inje kada se stroj zaustavi na stovari{tu i zavr{ava kada krene sa stovari{ta

Moving unloaded, F–H Prazna vo`nja, F–H

Starts when the machine moves from the landing and ends when the machine stops at the cutting/loading area Po~inje kada stroj kre}e sa stovari{ta i zavr{ava kada se zaustavlja na mjestu sje~e/utovara

Miscellaneous, F–H Razno, F–H

Other activities, e.g. picking up dropped bunches, etc Ostale aktivnosti, npr. podizanje ispalih sve`njeva

Delays, F–H Zastoji, F–H

E.g. repairs and personal breaks Npr. popravci i osobni odmori

Croat. j. for. eng. 33(2012)1

Productivity and Profitability of Forest Machines in the Harvesting ... (25–37)

The system analysis boundaries were defined to include harvesting and forwarding of the biomass piled at roadside. The plantation size was set to 10 ha (cf. Rosenqvist et al. 2000), giving a forwarding distance of 250 m. The analyses were based on the average productivity of the harvester and harwarder when harvesting six and three double rows, respectively. The conversion of PW into Work Time including delays shorter than 15 min (WT) (IUFRO 1995) was based on the maximum proportion of delay time recorded in the field study for each system. The interest rate was set to 6% and the calculation was made according to Harstela (1993). The purchase prices were set for the harvester, forwarder and harwarder to €285,000, €225,000 and €270,000, respectively (cf. Laitila 2008). The annual utilization time (AU) for the harvester, forwarder and harwarder were set to 2,361 WT-hours/year, 2,500 WT-hours/year and 2,430 WT-hours/year, respectively (cf. Nurminen et al. 2009). The AU for the harwarder was calculated as an average of the harvester and forwarder values. The economic lifetime was set to 6 years and the salvage value was set to 20% of the purchase price. The operator costs were set to 20 €/WT-hour. The calculated hourly operating costs of the harvester, forwarder and harwarder were 85.2 €/WT-hour, 70.4 €/WT-hour and 79.6 €/WT-hour, respectively. The relocation cost was set to 200 € per machine and relocation. The gross income was based on current market price for un-comminuted tree parts delivered at road side of 21.0 €/m3solid (Anon 2010). A conversion rate of 397 OD kg/m3solid was used (cf. Nurmi 1995). The net income of the removal was calculated as the difference between the roadside gross income and the harvesting costs (including relocation costs).

3. Results – Rezultati The harvester was studied for 19.67 WT hours, of which delay time accounted for 0.3%. The harvested area was 1.46 ha. The PW time consumption per ha in the N and O area was 13.2 (sd = 1.4) and 13.5 (sd = 1.2) hours, respectively, which corresponds to respectively 0.36 and 0.24 PW-hours/OD t. The average productivity of the harvester was 3.5 OD t/PW-hour. The biomass density (factor a) and the number of harvested rows (factor b) had significant effects on productivity (p < 0.001 and p = 0.036, respectively). Consequently, the productivity was 54.4% higher in the O area than in N, and it was 9.3% higher when harvesting five rather than six rows. The working method (factor g) had no significant effect on productivity (p = 0.132). No significant block or interaction effects on PW time consumption per hectare were found. Croat. j. for. eng. 33(2012)1

Fulvio Di Fulvio et al.

The average number of felled and accumulated stools per crane cycle in the N and O areas was 13.2 and 8.8, respectively, and the difference was significant (p < 0.001). The average amount of biomass harvested in a full crane cycle in the N and O areas was 34.3 and 39.6 OD kg, respectively, and the difference was significant (p = 0.018). The total time consumption per stool did not differ significantly for any of the eight examined combinations of the tree factors (Table 4). However, the greater biomass density (factor a) in O areas (relative to N areas) resulted in a 10.6% and significant increase (p = 0.019) in the PW time consumption per stool. Harvesting five rows instead of six (factor b) caused an 8.9% significant reduction (p = 0.029) in PW time per stool. The forwarder was studied for 7.64 WT-hours, of which delay time accounted for 8%. In total 25 full loads were loaded, forwarded to roadside and un-loaded. At a hauling distance of 250 m, the time required for forwarding averaged 21.8 PW-min per load, which corresponds to a productivity of 7.2 OD t/PW-hour. The corresponding PW time consumption per hectare in the N and O area is then 5.0 (0.5) and 7.8 (0.7) hours, respectively. A full load averaged 2.6 OD t (5.3 fresh t), which corresponds to 38% of the machine’s load capacity. The load size reached 2.5 and 2.7 OD t (4.8 and 5.7 fresh t), respectively, in the N and O area, the difference in load size was not significant (p = 0.100). To reach a full load in the N and O area, in average 15 and 13 crane cycles were required, respectively. The average forwarding distance was 163 m (min. 32 and max. 317 m). An average strip road length of 47 m was required to achieve a full load. The forwarder’s average moving speed during productive work was 1.2 m/s when unloaded and 1.0 m/s when loaded. The average calculated bulk density of a full load was 109 OD kg/m3 (220 fresh kg/m3). Unloading took 4.66 PW-min per load on average (1.79 PW-min/OD t) and required an average of 10.8 crane cycles; the mass handled per crane cycle was 0.25 OD t. Miscellaneous time accounted for 0.58 PW-min per load on average (0.22 PW-min/OD t). Loading and moving while loading accounted for 7.39 and 1.36 PW-min per load (2.84 and 0.52 PW-min/OD t), respectively. The biomass density and number of rows (factors a and b) did not significantly affect the total time spent in loading and moving while loading in terms of PW-time/OD t. However, in the O area, the loading work element took 18% longer than was the case in the N area, and this difference was significant (p = 0.026) (Table 5). The harwarder was studied for 15.09 WT-hours, of which delay time accounted for 4%. It harvested an area of 0.29 ha. In total, 8 full loads were produced. At a hauling distance of 250 m, the producti-

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Productivity and Profitability of Forest Machines in the Harvesting ... (25–37)

Table 4 Productive work time (PW) consumed per stool (s/stool) during harvester operation Tablica 4. Proizvodno radno vrijeme (PW) utro{eno po panju (s/panj) za vrijeme rada harvestera Factor, a Faktor, a B

Normal, N Normalno, N 5 rows – 5 redova

Overgrown, O Preraslo, O 6 rows – 6 redova

5 rows – 5 redova

6 rows – 6 redova

Forward Ispred

Side to side Strana na stranu

Forward Ispred

Side to side Strana na stranu

Forward Ispred

Side to side Strana na stranu

Forward Ispred

Side to side Strana na stranu

n=3

Boom out Prazan kran

0.304a

0.341a

0.310a

0.434a

0.471a

0.461a

0.530a

Felling and accumulating Sje~a i kumuliranje

2.415ab

2.241b

2.704ab

2.758ab

2.591ab

2.338b

2.907a

2.466ab

Boom in Puni kran

0.461a

0.466a

0.521a

0.420a

0.593a

0.556a

0.621a

0.632a

Moving Kretanje

0.120ab

0.080b

0.082b

0.121ab

0.179a

0.103b

0.096b

Miscellaneous Razno

0.028a

0.000a

0.011a

0.022a

0.009a

0.017a

0.044a

0.035a

Total time Ukupno vrijeme

3.327a

3.168a

3.657a

3.592a

3.747a

3.561a

4.135a

3.760a

Total PW time consumption per stool, p-values: Factor a = 0.019, Factor b = 0.029, Factor g = 0.176, Factor a × b = 0.769, Factor a × b = 0.551, Factor b × g = 0.866, Factor a × b × g = 0.615, Block = 0.444 The p-values in bold indicate significant differences (p £ 0.05). Different superscript letters row-wise indicate significant (p £ 0.05) differences between treatments according to Tukey’s simultaneously test of means Ukupno PW utro{eno po panju, p-vrijednosti: faktor a = 0.019, faktor b = 0.029, faktor g = 0.176, faktor a × b = 0.769, faktor a × b = 0.551, faktor b × g = 0.866, faktor a × b × g = 0.615, blok= 0.444 p-vrijednosti ozna~ene poludebelo pokazuju zna~ajne razlike (p £ 0.05). Razli~ita slova u eksponentu po redovima pokazuju zna~ajne (p £ 0.05) razlike izme|u postupaka prema Tukeyevu testu

Table 5 Productive work time (PW) consumed by individual work elements in the operation of the forwarder when loading and moving while loading. The table shows the PW time consumed for different biomass densities (factor a, which can be either normal (N) or overgrown (O)) and the effects of operational factors, including the biomass concentration along strip roads, pile size, number of piles per crane cycle, and machine position. Standard deviations are given within brackets Tablica 5. Proizvodno radno vrijeme (PW) utro{eno po pojedinim radnim elementima u radu forvardera kod utovara i kretanja pri utovaru. Tablica pokazuje PW utro{eno za razli~ite gusto}e biomase (faktor a, koji moè biti ili normalno (N) ili preraslo (O)) i utjecaje radnih ~imbenika uklju~uju}i koncentraciju biomase pored putova, veli~inu sloàja, broj sloàja po ciklusu krana i poziciju stroja. Standardne su devijacije dane u zagradama Factor a – Faktor a

Normal, N – Normalno, N

Overgrown, O – Preraslo, O

n = 12

min/OD t

2.61 (0.46)

Moving while loading – Kretanje pri utovaru

0.54 (0.13)

17.1

0.51 (0.09)

Sum of Loading and Moving while loading – Zbroj utovara i kretanja pri utovaru

3.15 (0.54)a

100

3.58 (0.53)a

Loading – Utovar

82.9

3.07 (0.47)

85.8

14.2 100

Biomass concentration, OD t/100 m – Koncentracija biomase, OD t/100 m

3.96 (0.38)

6.16 (0.59)

Pile size, OD t – Veli~ina slo`aja, OD t

0.17 (0.03)

0.23 (0.02)

No. crane cycles/pile – Broj ciklusa krana/slo`aj

1.00 (0.00)

1.08 (0.10)

No. piles/machine position – Broj slo`ajeva/pozicija stroja

1.15 (0.14)

1.12 (0.14)

Different superscript letters row-wise indicate significant (p £ 0.05) differences between treatments according to Tukey’s test of means Razli~ita slova u eksponentu po redovima pokazuju zna~ajne (p £ 0.05) razlike izme|u postupaka prema Tukeyevu testu

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Productivity and Profitability of Forest Machines in the Harvesting ... (25–37)

vity in the N and O area was 0.75 and 1.02 OD t/PW-hour, respectively. Consequently, the PW time per ha in the N and O area was 47.8 (sd = 1.9) and 54.9 (sd = 4.7) hours, respectively. The average hauling distance was 183 m (min. 45 m and max. 280 m). On average, the harwarder moved at a speed of 1.2 m/s while unloaded and 1.0 m/s while loaded. The average load mass was 1.8 OD t (3.6 t of fresh biomass), which corresponds to 26% of the machine’s load capacity. The average calculated bulk density of a full load was 74 OD kg/m3 (148 fresh kg/m3). Unloading took 7.08 min/load (3.93 min/OD t) on average, and required an average of 17 crane cycles; the mean handled mass per crane cycle was 0.11 OD t. Miscellaneous time accounted for 0.44 minutes per load (0.25 min OD/t). The number of harvested rows (factor b1) had no significant effect on total PW time consumption in the O area. The biomass density (factor a) had a significant effect on PW time consumption (p < 0.001), and was 42% higher in the N area compared to O area (Table 6). The mean handled mass per crane cycle during felling and loading was 27 OD kg; for the N area (23 OD kg) it differed significantly (p = 0.042) from that for the O area (28 OD kg). The mass moved by the crane during the felling and loading cycle was 74% lower than the corresponding mass while unloading. The number of stools handled per crane cycle was 9.0 and 6.3 in the N and O area, respectively, and the difference was significant (p = 0.034).

Table 6 Productive work time (PW) consumed by individual work elements in the operation of the harwarder and in total, for different biomass densities (factor a; normal (N) and overgrown (O)) Tablica 6. Proizvodno radno vrijeme (PW) utro{eno po pojedinim radnim elementima u radu harvardera i ukupno, za razli~ite gusto}e biomase (faktor a, normalno (N) ili preraslo (O)) Factor a – Faktor a

Normal, N Normalno, N

Overgrown, O Preraslo, O

n=2

n=6

min/OD t

Boom out Prazan kran

4.88 (0.76)a

6.8

4.23 (1.03)a

8.4

Felling – Sje~a

57.25 (1.36)a

80.4

38.34 (2.58)b

76.2

9.7

5.85 (0.70)

Moving while loading 2.19 (0.18)a Kretanje pri utovaru

3.1

1.89 (0.43)a

3.8

71.23 (1.70)a

100

50.32 (2.99)b

100

Loading – Utovar

Sum – Zbroj

6.91 (0.24)

11.6

Different superscript letters row-wise indicate significant (p = 0.05) differences between treatments according to Tukey’s simultaneously test of means Razli~ita slova u eksponentu po redovima pokazuju zna~ajne (p = 0.05) razlike izme|u postupaka prema Tukeyevu testu

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Table 7 Gross incomes, costs and net incomes for the two-machine and harwarder systems in normal (N) and overgrown (O) willow plantations. OD = oven-dry Tablica 7. Bruto prihod, tro{kovi i neto dobit za sustav s dvama strojevima i harvarder u normalnim (N) i preraslim (O) planta`ama vrba. OD = suha tvar Harvester and forwarder Harwarder – Harvarder Harvester i forvarder Normal, N Overgrown, O Normal, N Overgrown, O Normalno, N Preraslo, O Normalno, N Preraslo, O Gross income, €/ha Bruto prihod, €/ha Cost, €/ha Tro{kovi, €/ha Cost, €/ODt Tro{kovi, €/ODt Net income, €/ha Neto dobit, €/ha Net income, €/ODt Neto dobit, €/ODt

1 904

2 962

1 904

2 962

1 721

1 934

3 987

4 572

111

184

1 028

–2 082

–1 610

–58

–28

The mean height of the harvested stumps was 18.2 cm (min. 3 cm, max. 58 cm and median 17.5 cm). The proportion of damaged stumps was 29.9%. No significant differences in either stump height or proportion of damaged stumps was observed for any treatment factors or machine/felling head types. The average depth of the machines’ tracks after the work was complete was 6 cm (min. 0 cm, max. 28 cm and median 1.5 cm). Economic Analysis In the two-machine system, the harvester operation accounted for 75% of the total cost of the work in the N area and 67% in the O area. The total operating costs per hectare for the two-machine system in the N and O areas were respectively 43% and 42% lower than those for the harwarder (Table 7). In the O area, the cost per harvested OD t for the two-machine system and for the harwarder was respectively 73% and 74% lower than the corresponding cost in the N area. The cost to gross income ratio was below 100% for the two-machine system, but above 100% for the harwarder. The net income per OD t for the two machine system was 2.6 times higher in the O area than in the N area.

4. Discussion – Rasprava The harvester The biomass density (OD t/ha) (i.e. tree size) had only a minor, non-significant, effect on the felling-bunching work time consumption per ha. The har-

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Productivity and Profitability of Forest Machines in the Harvesting ... (25–37)

vester’s productivity was therefore 54% higher in the O areas than in the N areas as the biomass density in O areas was 57% higher than that in N areas. Similar results of increases in harvester productivity have been reported in the thinning of forest stands for energy-wood (Kärhä et al. 2005, Di Fulvio et al. 2011). Fewer harvested rows had a significant reduction effect on the harvester’s time consumption per ha, which was due to the use of relatively shorter crane extensions (cf. Ovaskainen 2009). In this case the driver had a clearer view of the cutting device and the progress of the work, resulting in more accurate control over the felling process. The working method »forward« had no significant effect on the harvester’s time consumption but with this method it was easier to grab a single stool at a time than working perpendicularly to the rows (side to side) (cf. Fig. 2). Visual inspection indicated that the felling speed during a crane cycle was slightly reduced cutting stems larger than ca. 3 cm dsh, which in turn facilitated the possibility to manage a proper accumulation of the cut stems (i.e. at higher speeds it was more difficult to manage a proper accumulation). This suggests that modification of the accumulating function might be necessary in order to fully exploit the potential of this technology when harvesting at higher speeds. To increase the potential of AFHs, the felling and accumulation of trees must be performed in a continuous movement, for instance by using the boom-corridor technique (cf. Bergström 2009, Forsberg and Wennberg 2011). The harvester operator experienced a more stressful work that required a greater degree of concentration in the current study (i.e. clear cutting of SRWC) compared to energy-wood thinning. This was mainly due to the handling of many more trees/stems per hour of work time. This problem could possibly be reduced by increasing the automation of the felling process, e.g. by having the driver control only the felling direction and speed, with grabbing, cutting and the accumulation of stems being performed automatically. The forwarder The biomass density and number of harvested rows did not significantly affect the work time required per load for the forwarder. However, the higher biomass concentration in the O area significantly increased the loading time consumption per OD t. This is because the pile size in the O area was 42% larger than that in the N area; the piles in the O area were thus larger than the grapple area and multiple crane cycles were required per pile. The average mass of the piles in the O area, when harvesting six rows, was 487 kg. The force required to lift such piles, when they are located ca. 3 m away from the

machine, is much less than the studied machine’s capacity (1500 kg at 4.5 m from the crane base). The grapple area was therefore deemed to be the limiting factor in this work; it is expected that the efficiency of forwarding in the O areas could be increased by using a grapple with a larger grapple area that would be able to load the larger piles using only one crane cycle. In this case, estimates based on the field study data suggest that the time consumption for loading and moving while loading would have been decreased by 6% if all piles had been loaded with only one crane cycle. On the basis of the field data, it was determined that each stoppage of the machine consumed 3.5 s on average, which was added to the »moving while loading« time element. Suppose that in the O area, the harvester produced piles whose sizes corresponded to either 1 or 2 full forwarder grapples (0.216 or 0.432 OD t), with the density of piles per loading position being high in the former case and low in the latter. In this case, it would be possible to describe the time spent moving while loading as a function of the spacing between the piles. The production of larger and more widely-separated piles would decrease the total time spent on loading and moving while loading per OD t forwarded by 3%. Overall, these observations indicate that the size of the piles produced by the harvester must match the capacity of the forwarder’s grapple in order to maximise the efficiency of forwarding, i.e. the work of the harvester and the forwarder must be synchronized (cf. Gullberg 1997). The harwarder The harwarder was equipped with an accumulating felling-grapple designed for both felling and loading. However, because of its dual-purpose nature, the felling-grapple is less efficient at either task than purpose-specific heads. That is to say, the number of stools felled per crane cycle with the felling-grapple was 30% lower than the corresponding number achieved with the harvester’s AFH, and the grapple load during unloading contained 57% less biomass than that achieved using the slash grapple employed in forwarding operations. In addition, the mass of a full harwarder load was 32% lower than that of a full forwarder load. The difference in load mass can be explained by the fact that the forwarder loaded pre-bunched stems, which were thus somewhat compressed, while the harwarder performed direct-loading. It might be possible to increase the harwarder payload by using load compression devices, such as flexible stakes attached to the bunk of the machine (cf. Bergström et al. 2010). The time spent on felling per stool was 3.9 times higher for the harwarder than for the harvester (9.8 s/stool comCroat. j. for. eng. 33(2012)1

Productivity and Profitability of Forest Machines in the Harvesting ... (25–37)

pared to 2.5 s/stool). It is reasonable to assume that the felling speed of the harwarder could be significantly increased by using more advanced technology that is better suited to industrial forestry, such as the Ponsse EH25 felling-grapple. If we assume that the harwarder’s felling speed could be doubled in this way, the time consumption per stool would be 4.6 s and 5.2 s, respectively, in the N and O areas. Such increases in felling efficiency would in turn increase the machine’s productivity in the N and O areas by 59% and 52%, respectively, relative to the results obtained in the field study. An additional increase in productivity could also be expected with a purpose built harwarder; the one used in this work was a standard forwarder with a crane designed only for loading. Work quality The operators of the harvester and harwarder were instructed to cut the stools to an above-ground height of less than 10 cm. However, both felling heads produced average stump heights in excess of this level. This was partially due to the snow that covered the soil when the harvesting was performed, which made it difficult to assess the true ground level. It was also observed that when stools were cut row-wise, the stump height rose as the boom reach increased, i.e. the stumps were shorter close to the machine and taller further away from it. The average proportion of damaged stumps was 30%, which is relatively high (cf. Hytönen 1994). It was observed that, when using the harvester, it was possible to grab more than one stool at a time with the AFH, which caused the stems to bend slightly while being cut; this in turn caused the stools to split. The tracks left by the machines’ wheels were relatively shallow. Harvesting was performed at a time when the soil was partially frozen, which had a positive effect on its bearing capacity. Using tracks on the forwarder’s wheels (bogies) would significantly reduce the pressure it exerts on the ground, which would be especially useful on wet soils. Economic Analysis When using forest machines to harvest SRWC, the productivity can be expected to increase with the size of the stems up to a certain point. The two-machine system was found to be profitable in both the normal and over-gown areas, while the harwarder produced a loss in both. The conventional direct chipping system reaches an average productivity of about 16 OD t/WT hour under conditions where the crop yield is 25 OD t/ha (Danfors and Nordén 1995). It would therefore be expected to achieve greater incomes than with either of the studied forest machiCroat. j. for. eng. 33(2012)1

Fulvio Di Fulvio et al.

nes systems under normal and somewhat overgrown conditions (cf. Danfors and Nordén 1995). However, as the amount of biomass harvested increases, the profitability of the forest systems increases while the convenience and ease of operation of the conventional systems is expected to decline. This suggests that the use of two-machine systems in more heavily overgrown willow plantations could be even more efficient than that of conventional direct chipping systems.

5. Conclusions – Zaklju~ci This study shows that a thinning harvester’s work time consumption per hectare in the felling and bunching of stems in SRWC plantations is meagerly affected by stem sizes or biomass density, which gives a harvesting productivity increase almost proportional to the increase in biomass density. The work time consumption of the harwarder increased significantly with biomass density, while the increase was only minor for the forwarder. That suggests that a harvester-forwarder system productivity would be expected to increase significantly when harvesting stands with average diameters greater than 5 cm at stump height that are more overgrown than those studied. The net income obtained using the harvester-forwarder system under the studied conditions was positive; however, the net income achieved using the harwarder system was negative. This study indicates that, when dealing with highly overgrown willow plantations, where ordinary forage harvesters cannot be used, current forest machines adapted for harvesting small diameter trees may offer an efficient and economically viable alternative. Further development of techniques and working methods for the use of forest machines can be expected to increase their efficiency and reduce their harvesting costs.

Acknowledgements – Zahvala This study was financed by the Swedish Energy Agency »Energimyndigheten«. We thank Mr. Hans Eriksson, Västeräng Lantbruk AB, for the assistance in field experiments.

6. References – Literatura Anon. 2010: Prislista energisortiment. [Price list on energy assortments] Prislista 158E 04. Norra Skogsägarna. http:// norraskogsagarna.se [accessed 2011-03-10]. Bergström, D., 2009: Techniques and systems for boomcorridor thinning in young dense forests. Doctoral thesis. Acta Universitatis Agriculturare Sueciae, 87 p.

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Bergström, D., Nordfjell, T., Bergsten, U., 2010: Compressing processing and load compression of young Scots pine and birch trees in thinnings for bioenergy. International Journal of Forest Engineering 21(1): 31–39. CEN/TS 14774-2, 2004: Solid biofuels – Methods for the determination of moisture content – Oven dry method – Part 2: Total moisture – Simplified method. Danfors, B., Nordén, B., 1995: Sammanfattande utvärdering av teknik och logistik vid salixskörd. Jordbrukstekniska institutet. [Summarizing evaluation of techniques and logistic for harvesting of willow]. Uppsala, JTI-rapport, 210 p. Di Fulvio, F., Kroon, A., Bergström, D., Nordfjell, T., 2011: Comparison of energy-wood and pulpwood thinning systems in young birch stands, Scandinavian Journal of Forest Research, 26(4): 339–349. Forsberg, J., Wennberg, R., 2011: Teknikutveckling av aggregat för kontinuerlig ackumulerande skörd i unga skogar. [Technical development of a felling head for continuing accumulation at harvest in young forests] Examensarbete. Luleå tekniska universitet. Harstela, P., 1991: Work studies in forestry. University of Joensuu Faculty of Forestry. Joensuu. Finland. Silva Carelica 18, 41 pp. Harstela, P., 1993. Forest work science and technology. University of Joensuu Faculty of Forestry. Joensuu. Finland. Part 1. Silva Carelica 25, 113 pp. Hytönen, J., 1994.: Effect of cutting season, stump height and harvest damage on coppicing and biomass production of willow and birch. Biomass and Bioenergy 6(5): 349–357 IUFRO 1995: WP 3.04.02. Forest work study nomenclature. Test edition valid 1995–2000. Department of Operational Efficiency, Swedish University of Agriculture Sciences, Garpenberg, 16 pp. ISBN 91-576-5055-1. Laitila, J., 2008: Harvesting technology and the cost of fuel chips from early thinnings. Silva Fennica 42(2): 267–283. Magnusson, L., 2009: Teknik för skörd av Salix: status och utvecklingsbehov [Technique for harvesting of willow:

status and need of development]. Slutrapport 2009–05–20. EnerGia Konsulterande Ingenjörer AB. Stockholm. Mitchell, C. P., Stevens, E. A., Watters, M. P., 1999: Short-rotation forestry – operations, productivity and costs on experienced gained in the UK. Forest Ecology and Management 121 (1–2): 123–136. Mola-Yudego, B., 2011: Trends and productivity improvements from commercial willow plantations in Sweden during the period 1986–2000. Biomass and Bioenergy 35 (1): 446–453. Nordh, N., Dimitriou, I., 2003: Harvest techniques in Europe. IEA Bioenergy, Task 30. Short Rotation Crops for Bioenergy: New Zealand, pp. 115–120. Nurmi, J., 1995: The effect of whole-tree storage on the fuelwood properties of short-rotation Salix crops. Biomass and Bioenergy 8(4): 245–249. Nurminen, T., Korpunen, H., Uusitalo, J., 2009: Applying the activity-based costing to cut-to length timber harvesting and trucking. Silva Fennica 43(5): 847–870. Ovaskainen, H., 2009: Timber harvester operators’ working technique in first thinning and the importance of cognitive abilities on work productivity. Doctoral dissertation. Dissertationes Forestales 79. ISSN 1795-7389. ISBN 978951-651-247-4. Rosenqvist, H., Roos, A., Ling, E., Hektor, B., 2000: Willow growers in Sweden. Biomass and Bioenergy 18(2): 137–145. Sims, R., 2002: The brilliance of bioenergy in business and in practice, James & James (Science Publishers) Ltd, Unithed Kingdom. ISBN 1-902916-28 X. Spinelli, R., Nati, C., Magagnotti, N., 2008: Harvesting Short-Rotation Poplar Plantations for Biomass Production. Croatian Journal of Forest Engineering 29 (2): 129–139. Talbot, B., Nordfjell, T., Suadicani, K., 2003: Assessing the utility of two integrated harvester-forwarder machine concepts through stand-level simulation. International Journal of Forest Engineering 14(2): 31–43. Verwijst, T., Telenius, B., 1999: Biomass estimation procedures in short rotation forestry. Forest Ecology and Management 121 (1–2): 137–146.

Sa`etak

Proizvodnost i profitabilnost {umskih strojeva u iskori{tavanju normalnih i preraslih plantaà vrba U [vedskoj se plantaè vrba u kratkim ophodnjama (PVKO) obi~no iskori{tavaju izravno iveranjem, uz primjenu krmnih kombajna opremljenih zaglavljima za rezanje drva i prijamnim bunkerima za transport usitnjene biomase do ceste. Krmni kombajni kori{teni u PVKO imaju nedostatak u tome {to ne mogu u~inkovito prikupljati stabljike deblje od 6 do 7 cm u visini panja. Moè se o~ekivati da }e u budu}nosti plantaè vrbovih panja~a postizati vi{e prinose biomase zbog uzgajanja novih klonova te }e se prosje~ni promjeri pridobivanih stabala vjerojatno pove}ati, {to }e stvoriti potrebu za takvim kombajnima koji mogu raditi s ve}im stablima. Mogu}a alternativa u

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Productivity and Profitability of Forest Machines in the Harvesting ... (25–37)

Fulvio Di Fulvio et al.

pridobivanju biomase na takvim plantaàma mogu biti {umski strojevi s ugra|enim akumulativnim sje~nim glavama (ASG) razvijenim za sje~u malih stabala za bioenergiju u prvim proredama. Cilj je ovoga istraìvanja bio utvrditi utro{ak vremena i usporediti tro{kove primjene dvaju sustava {umskih strojeva u normalnim (N) i preraslim (O) PVKO, pri ~emu je gusto}a promatrane biomase iznosila 36 i 56 tona suhe drvne tvari po hektaru. Prvi strojni sustav uklju~io je harvester i forvarder, a drugi se sastojao od harvardera (sustav od jednoga stroja). Sje~a i usnopljivanje pomo}u harvestera istraìvani su kao funkcija gusto}e biomase, broja posje~enih redova i smjera sje~a–usnopljivanje. Potro{nja radnoga vremena forvardera analizirana je s obzirom na gusto}u biomase i broj poètih redova. Potro{nja radnoga vremena harvardera analizirana je u ovisnosti o gusto}i biomase i broja posje~enih redova. Proizvodnost je harvestera bila 54 % ve}a na O povr{ini nego na N povr{ini, i iznosila je 9 % vi{e pri pridobivanju pet nego {to je pri pridobivanju {est duplih redova. Smjer sje~a–vezanje u snopove nije imao zna~ajan utjecaj na proizvodnost harvestera. Gusto}a biomase i broj sje~enih redova nisu zna~ajno utjecali na utro{ak vremena po tovaru forvardera. Kod harvardera gusto}a je biomase zna~ajno utjecala na potro{nju vremena po tovaru. Ono je u usporedbi s O povr{inom bilo 42 % ve}e na N podru~ju, dok broj posje~enih redova nije imao signifikantan utjecaj. Harvarder je bio opremljen s akumulativnom sje~no-hvatnom glavom koja je dizajnirana za oboje, i za sje~u i za utovar, i tada je vrijeme utro{eno na sje~u po panju bilo 3,9 puta ve}e nego za harvesterovu ASG. Pri pridobivanju i izvoènju biomase na udaljenosti od 250 m proizvodnost sustava s dvama odnosno s jednim {umskim strojem iznosila je prosje~no 2,3 (sd = 0,6) odnosno 0,9 (sd = 0,2) tona suhe drvne tvari/proizvodni radni sat. Gusto}a biomase ili veli~ina stabla imali su sporedni u~inak na potro{nju vremena po hektaru za sustav s dvama strojevima, ali su zato zna~ajni kod sustava s jednim strojem. Proizvodnost sustava s dvama strojevima i sustava s jednim strojem u O podru~ju iznosila je u usporedbi s N povr{inom 40 % odnosno 36 % vi{e. Ukupni tro{kovi rada po hektaru za sustav s dvama strojevima na N i O povr{inama bili su za 43 % odnosno 42 % niì nego tro{kovi rada harvardera. Neto je dobit bila pozitivna kada je kori{ten sustav harvester–forvarder, a kada je primijenjen harvarder, neto je dobit bila negativna. Neto dobit po toni suhe tvari kod sustava s dvama strojevima bila je 2,6 puta ve}a u O podru~ju nego je to u N podru~ju. Zaklju~uje se da s pove}anjem koli~ine biomase koja se pridobiva profitabilnost {umskih sustava raste, dok se za konvencionalne sustave o~ekuje da pogodnost i jednostavnost njihova rada opadaju. Prema tome, ako se radi o vi{e preraslih plantaà nego {to je to u primjeru, {umski strojevi i posebno sustav harvester–forvarder mogu ponuditi u~inkovitu i ekonomi~nu alternativu uobi~ajenim krmnim kombajnima. Daljnji razvoj tehnika i radnih metoda u upotrebi {umskih strojeva moè pridonijeti o~ekivanomu pove}anju njihove u~inkovitosti i smanjenju tro{kova pridobivanja biomase. Klju~ne rije~i: analiza sustava, studij vremena, proizvodnost, harvester, forvarder, harvarder

Authors’ address – Adresa autorâ:

Received (Primljeno): September 30, 2011 Accepted (Prihva}eno): February 07, 2012 Croat. j. for. eng. 33(2012)1

Fulvio Di Fulvio, PhD. e-mail: fulvio.di.fulvio@slu.se Dan Bergström, PhD. e-mail: dan.bergstrom@slu.se Kalvis Kons, MSc. e-mail: kalvis.kons@slu.se Prof. Tomas Nordfjell, PhD. e-mail: tomas.nordfjell@slu.se Swedish University of Agricultural Sciences Department of Forest Resource Management Skogsmarksgränd, SE-901 83 Umeå Sweden

Original scientific paper – Izvorni znanstveni rad

Productivity of Processing Hardwood from Coppice Forests Christian Suchomel, Raffaele Spinelli, Natascia Magagnotti Abstract – Nacrtak Approximately half of the Italian forest area is classified as coppice forest, mostly managed for the production of firewood. Chestnut (Castanea sativa Mill.) coppice stands make exception, as they also produce more valuable assortments, such as sawlogs, poles and fencing materials. Hence the significantly higher industrial activity in chestnut coppice stands, and the rapid introduction of mechanized harvesting. This study deals with four different harvester units used for processing (delimbing – bucking) chestnut trees from coppice stands, at the landing. For these four different machines, time studies were conducted in order to estimate productivity and compare the performance. The results show that the processors can reach high productivities (7.7 m3/ PMH0 –19.8 m3/PMH0). In one study the influence of tree form has been estimated, proving that the size of the branches and the shape of the stem have a significant effect on machine productivity. The difference can reach 2.3 m3/PMH0 for stems with a volume of 0.2 m3. Keywords: coppice forests, processor, CTL, time study, chestnut, harvester

1. Introduction – Uvod In Italy, coppice forests represent an important landscape element and a significant economic resource. 54.5% of the Italian forest area is classified as coppice forest. In the past, these stands were clear-cut at 15 to 30 year intervals, leaving between 50 and 90 standards per hectare, with the purpose of: a) allowing the progressive regeneration of the stool base, b) diversifying production and c) improving stand structure. Since regeneration is obtained through stool resprouting, these stands have a multiple stem structure. Despite a general trend towards conversion into high forests, the majority of these stands are still managed through coppicing. 21% of the Italian coppice forests are based on Mediterranean oaks, 18% on chestnut (Castanea sativa Mill.), 16% on oaks, 15% on beech (Fagus sylvatica L.), 19% on hornbeam (Carpinus betulus L.), 1% on riparian trees and 10% on other species (INFC 2005, FAO 2005). Chestnut coppice is widespread all over Italy, but is particularly common in the Regions of Piedmont, Tuscany, Latium, Campania and Calabria. Chestnut coppice is seldom converted into high forest, because coppice stands are much less vulnerable to chestnut blight (Cryphonectria parasitica) compared to chestnut high Croat. j. for. eng. 33(2012)1

forests. Assortments obtained from chestnut coppice are: sawlogs, poles, fencing, firewood and woodchips. Trees from coppice generally have small size and a basal sweep, since they grow as multiple stems from the tree stump. Stem crowding and basal sweep make mechanical felling difficult, which has slowed down the introduction of modern machinery to coppice management. However, most forest companies have recognized the crucial role of mechanization to increase work productivity and safety, so that a growing number of harvesters and processor heads are being deployed also in coppice operations. Felling is done by chainsaw to guarantee that the stump is cut near the ground level and that no fibers are pulled out. This research was conducted on four different processors, in order to evaluate the factors affecting the productivity of processing (delimbing – bucking) pre felled chestnut trees from coppice stands, at the landing. All trees were felled by chainsaw. Logging was done by tractor or by cable yarder, but extraction was outside the scope of this study. The research was conducted in cooperation between the Institute of Forest Utilization and Work Science of the University of Freiburg and CNR IVALSA.

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2. Material and Methods – Materijal i metode 2.1 Study layout – Prikaz istra`ivanja Many studies have already dealt with the productivity of harvesters, showing that the main parameters influencing productivity are stem volume or DBH (Diameter at Breast Height), tree species and harvesting intensity (Heinimann 2001). This study is specifically concerned with the processing (delimbing – bucking) of chestnut stems obtained from coppice stands. This work was generally conducted at the landing and therefore the main parameters expected to affect machine productivity are: stem volume, number of logs obtained from the stem, machine type. In addition, tree form was assumed to have a potentially significant effect on machine productivity, and was tested as a covariate in one of the studies composing the overall experiment.

2.2 Study sites and harvesting system Radili{ta i sustavi pridobivanja drva The authors studied four different harvesting machines processing pre felled chestnut trees from coppice at the landing in Northern (Piedmont) and Central (Tuscany and Emilia Romagna) Italy. The machines were: an Arbro 400S on a JCB 8052 excavator, a Foresteri RH 25 on a CAT 312 L excavator, a Lako 55 Premio on a JCB JS 180 NL excavator and a Timberjack 1270B dedicated harvester with John Deere 762C head. Even though one machine was a dedicated harvester, all machines were part of this study. Trees were processed at the landing so that all studied machines had little need for moving. Therefore, locomotion technology (tracks or wheels) was likely to have a very small impact on productivity levels. The Foresteri Study is described as two separate experiments: in the treatment »Foresteri 1« the machine was

Table 1 Site and study conditions Tablica 1. Mjesto i radni uvjeti Study Istra`ivanje

Foresteri 1

Foresteri 2

Area – Podru~je

Gaiole in Chianti (SI)

Machine – Stroj

Excavator – Bager CAT 312 L (71 kW, 16 t)

Head – Glava Methods Metoda Species – Vrsta

Assortments Sortimenti

DBH average D1,30 prosjek

Lako

JohnDeere

Arbro

Abbadia S. Salvatore (SI)

Monzuno (BO)

Armeno (NO)

Signorino (PT)

Excavator – Bager CAT 312 L (71 kW, 16 t)

Excavator – Bager JCB JS 180 NL (92 kW, 19 t)

Harvester Timberjack 1270B (170 kW, 19 t)

Excavator – Bager JCB 8052 (34 kW, 5 t)

Foresteri RH 25

Lako 55 Premio

John Deere 762C

Arbro 400S

Processing at cable yarder landing Izradba na pomo}nom stovari{tu `i~are

Processing at landing Izradba na pomo}nom stovari{tu

Chestnut – Kesten

Chestnut with some birch Kesten s brezom

Chestnut – Kesten

MDF pulpwood – Drvo za plo~e Poles – Stupovi 2,5 m, 15–20 cm Poles – Stupovi 3,5, 4,5 and 5,5 m (large 2 m, 8–12 cm 2.2 m long pulpwood; end up to 20 cm, small end 3,5, 4,5 and 5,5 m (large 3 m, 10–15 cm hornbeam and oak: 1,1 m not smaller than 10 cm end up to 20 cm, small end 5 m, 15–23 cm Process Random lengths – long firewood promjer na debljem kraju not smaller than 10 cm 5 m, 23–30 cm Izradba slu~ajnih duljina promjer na debljem kraju 2,2 m celulozno drvo; grab Pulpwood – Celulozno drvo <20 cm, a na tanjem >10 cm <20 cm, a na tanjem i hrast: 1,1 m ogrjevno drvo Tops for chip production >10 cm Tops for chip production Ovr{ine se iveraju Ovr{ine se iveraju Tops for chip production Ovr{ine se iveraju 11.9 ± 4.1 cm

19.8 ± 5 cm

15.2 ± 4.4cm

14.0 ± 3.7 cm

17.8 ± 4.3 cm

DBH (min.–max.)

4–33 cm

12–33 cm

8–34 cm

5–29 cm

8–38 cm

Cycles – Turnusi

528

136

242

840

195

Obs. time Snimljeno vrijeme

9.1 h

2.1 h

9.4 h

13.7 h

5.8 h

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working under a yarder, whereas in »Foresteri 2« it was tending to a skidder. Table 1 shows a synthetic description of study sites and machine characteristics.

2.3 Data collection – Prikupljanje podataka Time-motion studies were carried out in order to evaluate machine productivity and to identify the variables that are most likely to affect it. Cycle times were split into a number of time elements considered as typical of the working process (Table 2). Time elements were recorded with a Husky Hunter hand held field computer running Siwork3 timestudy software. For the purpose of the study, the harvested volume was measured directly after processing or it was calculated from the diameter at breast height (DBH), using volume tables. In the later case, between 10 and 20 tree heights and diameters were measured before processing the trees, in order to estimate a DBH-height curve. Using the calculated heights and measured DBH values, tree volumes could be estimated for each tree, using local volume tables. The DBH of each tree to be processed was marked on the stem or on the butt end, so that researchers could see and note it when recording time study data. In this study the productivity was estimated for the processed stem volume, excluding the volume eventually converted into chips (tops and branches). Waiting times were also excluded from calculations, because they originated from organizational causes and were not specifically related to the stems being processed or to the processing machines. Data were pooled together for statistical analysis, after adding an indicator variable describing the specific test, namely: Foresteri 1, Foresteri 2, Lako, John Deere and Arbro. The use of indicator variables was introduced in order to test the statistical significance

Christian Suchomel et al.

of categorical variables (here: machine type) in the regression analysis. The effect of tree form was investigated only in one test (Arbro), by introducing an ordinal covariable with 5 different levels, namely: Level 1 – Small branches, straight stems; Level 2 – Big branches or bad form; Level 3 – Big branches and bad form, or very big branches; Level 4 – Very big branches and bad form, or fork and big branches; Level 5 – Forked several times, or many big and very big branches. This approach is widely accepted, and is recurrent in the scientific literature on this specific subject (Spinelli et al. 2002).

2.4 Statistical analysis – Statisti~ka analiza Analysis of variance was used to identify the influence of nominal variables on the model. Regression techniques were used to determine the relationship between productivity and work conditions. Statistical analysis was conducted with software package SPSS 18.0 for Windows. The analytical procedure developed as follows (as proposed by Stampfer et al. 2010): 1 – Determining the statistical significance of co-variables through the analysis of variance; 2 – Testing non-linear relationships of co-variables; 3 – Analysis of the interactions between factors and co-variables; 4 – Regression analysis; 5 – Test of the regression model (residual analysis).

3. Results – Rezultati 3.1 Model calculation – Model kalkulacija Table 3 shows a first descriptive statistics of test results, whereas Table 4 presents the results of the regression analysis. Net productivity excluding delays can be modeled as follows:

Table 2 Time elements: definitions and breaking points Tablica 2. Radni zahvati: definicije i fiksa`ne to~ke Move Premje{tanje Grab Zahvatanje Process Izradba Stack Slaganje Product management Uhrpavanje sortimenata Other Ostalo

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Machine starts moving – machine stops Stroj se kre}e – stroj se zaustavlja Machine turns into direction of tree – head arms close around the tree Zauzimanje poloàja – harvesterska se glava zatvara Starts debranching and cross cutting – completes debranching and performs the last crosscut, severing the tree top Po~etak kresanja grana i trupljenja – zavr{etak kresanja grana i zadnjega trupljenja, odrezivanje ovr{ine Moves the top to the top pile – top falls on the pile, head arms open Premje{tanje ovr{ine na sloàj – ovr{ina pada na sloàj, harvesterska se glava otvara Take assortments and moves them to the appropriate pile – assortments dropped on the pile, head arms open Uhrpavanje sortimenata – sortiment pada na sloàj, harvesterska se glava otvara Other working steps Ostali radni zahvati

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Productivity of Processing Hardwood from Coppice Forests (39–47)

PROD = 17.551 + 4.839ln(vol) + 0.552LOGS + ((9.707 + 1.203ln(vol) ´ DF1) + ((20.022 + 6.432ln(vol) ´ DF2) + (10.123 ´ DJD) (1) where: PROD vol LOGS DF1 DF2 DJD

del can be used indifferently for Arbro and Lako, after setting all dummy variables to 0.

3.2 Machine productivity – Proizvodnost net productivity, m3/PMH0 stem volume, m3 number of logs per tree, n Dummy variable Foresteri 1 (1 = yes, 0 = no) Dummy variable Foresteri 2 (1 = yes, 0 = no) Dummy variable John Deere (1=yes, 0 = no)

With an adjusted R2 of 0.667, the equation shows a good fit. The p-value <0.001 demonstrates the high statistical significance of our model. A dummy variable for the Lako was not included into the model because the Arbro and the Lako had no significant differences in productivity. That means that the mo-

Fig. 1 shows the relationship between net productivity and stem size, calculated with functions presented above. The Foresteri appeared as the best performer, outproducing even the dedicated harvester. However, one must keep in mind the very wide spread of the data recorded for the dedicated harvester, which leaves significant room for adjustment. The Lako on a JCB JS 180 NL and the Arbro on a JCB 8052 excavator had the same productivity, despite the very different size and mechanical characteristics. Operator effect was most likely to account for this odd result.

Table 3 Descriptive statistics Tablica 3. Deskriptivna statistika

Cycle time [100/min] Vrijeme turnusa, cmin Productivity [m3/PMH0] Proizvodnost, m3/h Stem volume [m3] Obujam debla, m3 Logs [n/tree] Broj trupaca, n/stablu

Foresteri 1

Foresteri 2

Lako John Deere 5% Quantile – Mean – 95% Quantile 5. percentile – aritmeti~ka sredina – 95. percentil

Arbro

45–78–136

50–82–132

93–160–247

30–78–169

96–153–261

1.8–7.7–17.4

8.6–19.8–34.4

0.9–5.4–10.3

8.3–16.8–34.6

4.1–9.2–14.9

0.02–0.10–0.26

0.09–0.28–0.60

0.03–0.13–0.30

0.11–0.22–0.39

0.08–0.23–0.44

3.0–7.1–14,7

1.7–3.3–5.0

1.0–2.0–3,0

1.0–2.2–4.0

1.0–2.8–4.0

Mean – Aritmeti~ka sredina Trees/PMH0 [n] Broj stabala, n/h Logs/PMH0 [n] Broj trupaca, n/efek. satu

83.9

72.8

41.8

517

241

168

110

Table 4 Statistical significance of model variables Tablica 4. Statisti~ki zna~aj odabranih varijabli Model Model Constant – Konstanta ln(stem volume) Logs – Trupci Dummy Foresteri 1 Dummy Foresteri 2 Dummy John Deere Dummy Foresteri 1 × ln(stem volume) Dummy Foresteri 2 × ln(stem volume)

Non standardized coefficient Standardized coefficient Nestandardni koeficijenti Standardni koeficijenti Coefficient Std. error Beta Koeficijent Standardna pogre{ka 17.551 0.586 4.839 0.250 0.459 –0.552 0.055 –0.210 9.707 0.998 0.524 20.022 1.191 0.613 10.123 0.305 0.602 1.203 0.356 0.183 6.432 0.720 0.312

t-value t-vrijednost

Significance Zna~ajnost

29.926 19.386 –9.995 9.727 16.813 33.184 3.374 8.933

<0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001

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Christian Suchomel et al.

Fig. 1 Net productivity as a function of stem volume, for the different tests Slika 1. Neto proizvodnost u ovisnosti o obujmu debla za razli~ite studije

3.3 Breakdown of Cycle times – Ra{~lamba vremena turnusa In all five studies, »moving« time had a very low incidence over total cycle time, accounting for a proportion of 2.2% (Foresteri 1) to 8.5% (John Deere). The time for »grabbing« trees represented between 15% and 24% of the total net work time. In terms of absolute time, »grabbing« took between 12 and 23 100/min per cycle, with the Arbro and the Lako needing the longest time (23 100/min). »Processing« time represented the largest proportion of cycle time, in all studies, its percent contribution increased with tree DBH. In absolute terms, the average duration of processing time per tree was: Foresteri 1: 40 100/min. (with a average DBH of 11.9 cm), Foresteri 2: 49 100/min. (avg. DBH 19.8 cm), Lako: 96 100/min. (avg. DBH 15.2, John Deere: 34 100/min (avg. DBH 14 cm, Arbro 78 100/min. (avg. DBH 17.8 cm). »Stacking« tops after processing took between 6 and 11% of the total cycle time with the Foresteri, Lako and Arbro machines, but grew up to 23% with the John Deere dedicated harvester (18 100/min). The Lako also needed 15 100/min per cycle in order to stack tops after processing. »Product management« included moving processed assortments to different stacks and cleaning the work place. The contribution of this work step to the total cycle time was the highest with the Arbro, where it amounted to 18% (28 100/min. absolute time per cycle). In that case, the operator often grabbed the stems multiple times to »organize« the woodpile. The incidence of »other« Croat. j. for. eng. 33(2012)1

Fig. 2 Breakdown of net cycle time Slika 2. Ra{~lamba vremena turnusa time was the highest with Foresteri 1, because the processor worked by the cable yarder and performed additional ancillary tasks, such as moving the stems away from the yarder chute and to the work area.

3.4 Delays and daily work production – Prekidi i dnevni u~inak Delay events lasting no more than 15 minutes accounted for 10% to 20% of the total study time. The incidence of delays increased to 14 to 19%, if all events were included, regardless of their duration (Fig. 3). The daily work production is calculated by the equation (2): voltotal PRODday = (2) ( ttotal ´ 1.44) ´ 8 where: PRODday daily production (8 hour working day), m3 voltotal total processed volume, m3 ttotal total productive working time, PMH0 In this equation 31% delay time (multiplication factor 1.44) is included as the result of a meta analysis of delay times for processing (Spinelli and Visser 2008). The daily work production derive 42.9 m3/day for the Foresteri 1, 109.8 m3/day for the Foresteri 2, 93.1 m3/day for the John Deere, 30.0 m3/day for the Lako and 51.1 m3/day for the Arbro.

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Productivity of Processing Hardwood from Coppice Forests (39–47)

Fig. 3 Incidence of delay time on total study time Slika 3. U~estalost prekida u snimljenom vremenu

3.5 Effect of tree form on machine productivity Utjecaj oblika stabla na u~inak stroja The effect of tree form on productivity was estimated by correlation test for the Arbro study only, and it was taken as a general example. The five form factors described above showed a significant effect on productivity (confirmed by the Kendal-Tau and Spearman-Rho tests at the 0.01 level). Form factor was also used as an independent variable in multiple regression analysis, which returned an adjusted R2 = 0.775. The equation is represented in Fig. 4 and reads as follows: PRODArbro = 22.47 + 6.25 ´ ln(vol) – 0.864 ´ LOGS – 0.573 ´ f where: PRODArbro Net productivity, m3/PMH0 vol stem volume, m3 LOGS number of logs per tree, n f tree form

(3)

An ANOVA shows that 68.1% of the scattering can be explained by the variable stem volume, while the tree form explains 2.4% of the total variability and the number of logs 5%.

3.6 Costs – Tro{kovi The calculated unit costs per m3 ranged from 5.05 €/m3 (for Foresteri 2) to 18.50 €/m3 (for Lako). Detailed results and machine costs are shown in

Fig. 4 Net productivity as a function of stem volume and form, for the Arbro study Slika 4. Ovisnost neto proizvodnosti o obujmu i obliku debla za studiju Arbro Table 5. Very low cost was recorded especially for highly productive machines (Foresteri and John Deere) and cheap machines (Arbro). Hence, both strategies seem to give good results: the choice between them may depend on the annual work output. Croat. j. for. eng. 33(2012)1

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Table 5 Machine and unit costs Tablica 5. Tro{kovi stroja i jedini~ni tro{ak Machine Stroj Foresteri 1 Foresteri 2 Lako John Deere Arbro

Machine costs, €/h Tro{kovi stroja, €/h 100 100 100 130 70

Unit costs, €/m3* Jedini~ni tro{ak, €/m3 12.90 5.05 18.51 7.74 7.60

* unit costs calculated on the basis of productivity per PMH0 * jedini~ni tro{ak izra~unat je na osnovi u~inka po efektivnom satu rada

4. Discussion and Conclusions Rasprava i zaklju~ci The excavator-base Foresteri deployed at a yarder landing (Foresteri 1) processed chestnut trees with an average diameter at breast height (DBH) of 11.9 cm. Net productivity averaged 7.7 m3 and 89 trees per productive machine hour (PMH0), excluding delays. In most cases (457 cycles) the operator processed one tree at a time. In some other cases he processed 2 (61 cycles), 3 (27 cycles) or 4 (1 cycle) trees at a time. The calculation of different productivity functions for total processed tree volume by cycles could not reveal a difference in total productivity when processing more than one tree at a time. However, the productivity was higher when processing several small trees at a time, compared to processing them one by one. When teaming with a skidder (Foresteri 2), the same machine reached a net productivity of 19.8 m3 or 70 trees per productive machine hour. Productivity was higher than in the previous study, because trees were substantially larger, with an average DBH of 19.8 cm. Trees form was also better in the second study. Finally, the first study was conducted at a cable yarder landing, where the machine had to move with much care in order to avoid damage to the tower, the guy lines and other surrounding people and equipment. The productivity of the John Deere harvester was 16.8 m3 or 77 trees/PMH0. A single calculated correlation between stem volume and productivity was weak, due to a number of factors, and especially to the important and confounding effect of assortment type, which was not included in the regression. Nevertheless, the significance of this function is very high, due to the very large number of observations used to calculate it. The Lako harvester processed trees with an average DBH of 15.2 cm. The average tree volume was 0.13 m3. The productivity of this unit was 5.4 m3 or 41 trees per productive machine hour. Croat. j. for. eng. 33(2012)1

Christian Suchomel et al.

The Arbro 400S was the only stroke harvester in the study: as such, it fed stems through the delimbing knives using an alternating slide boom, rather than rollers, like the other units observed. The average net productivity was 9.2 m3 and 39 trees/PMH0. The range of tree DBH varied between 8 and 38 cm, with an average of 17.8 cm. The study showed that a full range of mechanical processors can be successfully deployed for handling whole chestnut trees, obtained from coppice harvesting. The processors reached high productivity and incurred low costs. Therefore, CTL technology offers a good alternative to motor-manual work in chestnut coppice stands to process trees at the landing (Spinelli et al. 2009). Working at the landing and using piles allowed the incidence of moving time, and increasing the proportion of the actual processing (delimbing-bucking) time. Furthermore, all machines worked in coppice clearcuts (the most common silvicultural treatment in coppice stands), with the advantage of a concentrated volume removal. On the other hand, coppice harvesting presents all the disadvantages related to small tree harvesting. Stem quality is another significant factor affecting productivity, as shown in the Arbro study. It should be particularly noted that different product strategies were followed in different studies, and that a more accurate comparison of machine productivity between tests could only be made if all machines were used to produce the same assortment range. The effect of assortment type on harvester productivity has already been shown by other studies, reporting productivity differences between 12 and 34% as a result of different product strategies (Emeryat et al. 1996 and 1997, Martin et al. 1996, Sauter and Grammel 1996, Spinelli and Spinelli 2000). Furthermore, productivity differences could partly derive from different operator skills. The 5 machines used for the study were operated by 5 different professionals, each representing a potential source of unaccounted variability (Gellerstedt 2002, Purfürst 2009). The operator effect has already been shown to affect machine productivity up to 40% (Ovaskainen et al. 2004). Therefore, the results of these studies must be interpreted with caution, avoiding definite conclusions.

Acknowledgements – Zahvala Thanks to the Deutsche Bundestiftung Umwelt (DBU) that financed the travel costs to Italy and made the exchange of information about harvesting and coppice between FOBAWI and CNR IVALSA possible. Special thanks also to the forest operators for their help and support in the field.

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5. References – Literatura Emeryat, R., Picorit, C., Reuling, D., 1996: L'allongement des longueurs de billions du pin maritime. AFOCEL Fiche Information-Forêt 531, 6p. Emeryat, R., Picorit C. and Reuling D., 1997: Perspectives de la mecanisation du bûcheronage du pin maritime. AFOCEL Fiche Information-Forêt 561, 6p. FAO, 2005: Global Forest Resource Assessment <http://www.fao.org/forestry/static/data/fra2005/global_tables/FRA_2005_Global_Tables_EN.xls> (Accessed 1 November 2010).

Technique in Thinnings. International Journal of Forest Engineering, 15(2): 67–77. Purfürst, T., 2009: Der Einfluss des Menschen auf den Harvester (The Influence of the operator on harvester). PhD thesis at the University of Dresden, 1–307. Sauter, U., Grammel, R., 1996: Konkurrierende Aufarbeitung von Nadelschwachholz in langer und kurzer Form mit Kranvollerntern in der Durchforstung (Competitive processing of conifer thinnings in long and short log lengths by crane harvesters). Forsttechnische Informationen (6/7): 68–76.

Gellerstedt, S., 2002: Operation of the single-grip harvester: motor-sensory and cognitive work. International Journal of Forest Engineering 13(2): 35–47.

Spinelli R., Magagnotti N., Nati C. 2009: Options for the mechanized processing of hardwood trees in Mediterranean forests. International Journal of Forest Engineering 20(1): 30–35.

Heinimann, H. R., 2001: Productivity of a cut-to-length harvester family – an analysis based on operation data. In: 24th annual meeting of the Forest Council on Forest Engineering COFE.

Spinelli, R., Owende, P., Ward, S., 2002: Productivity and cost of CTL harvesting of Eucalyptus globulus stands using excavator-based harvesters. Forest Products Journal 52(1): 67–77.

INFC, 2005: Ministero delle Politiche Agricole, Alimentari e Forestali. Inventario Nazionale delle Foreste e dei Serbatoi Forestali di Carbonio. <http://www.sian.it/inventarioforestale/jsp/home.jsp> (Accessed 1 November 2010).

Spinelli, R., Spinelli, R. 2000: L´allestimento meccanizzato del ceduo di castagno (Mechanical cross-cutting in a chestnut coppice). Monti e Boschi 51(1): 36–42.

Martin, P., Lapeyre, D., Restoy, G., Martinez, F., Guegand, G., 1997: Bûcheronage mécanisé en eclaircie de feuillus. Chantier de Tournay (65), AFOCEL Note technique CW 02/97, 22p. Ovaskainen, H., Uusitalo, J., Väätäinen, K. 2004: Characteristics and Significance of a Harvester Operators' Working

Spinelli, R., Visser, R. 2008: Analyzing and estimating delays in harvester operations. International Journal of Forest Engineering 19(1): 35–40. Stampfer, K., Leitner, T., Visser, R., 2010: Efficiency and Ergonomic Benefits of Using Radio Controlled Chokers in Cable Yarding. Croatian Journal of Forest Engineering 31(1): 1–8.

Sa`etak

Proizvodnost strojne izradbe tvrdih lista~a iz panja~a U Italiji su otprilike polovica {uma {ume panja~e ~ija je osnovna namjena proizvodnja ogrjevnoga drva. Za razliku od ostalih, panja~e pitomoga kestena (Castanea sativa Mill.) sluè za proizvodnju vrednijih sortimenata kao {to su pilanski trupci, stupovi, kolje za ograde, ogrjevno drvo i drvno iverje. Stoga je proizvodna aktivnost puno ve}a u kestenovim panja~ama te se uvode strojne metode pridobivanja drva. Cilj je ovoga istraìvanja odrediti proizvodnost ~etiriju razli~itih strojeva prilikom izradbe drva na pomo}nom stovari{tu. Istraìvane su ~etiri harvesterske glave Arbro 400S na bageru JCB 8052, Foresteri RH 25 na bageru CAT 312L, a Lako 55 Premio na bageru JCB JS 180NL i harvester Timberjack 1270B s harvesterskom glavom John Deere 762C. Istraìvanje je provedeno na pet razli~itih radili{ta (tablica 1), a bavi se isklju~ivo samo izradbom drva (kresanje grana i trupljenje). Svi su se radovi izvodili na pomo}nom stovari{tu, a glavni ~imbenici koji utje~u na proizvodnost bili su: obujam stabla, broj sortimenata dobivenih iz stabla, vrsta stroja. Dodatno je istraìvan utjecaj oblika stabla (debla) na proizvodnost stroja. Za izra~unavanje u~inka uziman je samo obujam izra|ene oblovine. Pri istraìvanju je proveden studij rada i vremena u kojem su radni zahvati podijeljeni prema tablici 2. Obujam je izra|enih sortimenata mjeren odmah nakon izradbe ili je bio ra~unat preko prsnoga promjera iz lokalnih obujamnih tablica koje su napravljene samo za ovo istraìvanje. Nakon prikupljanja podataka napravljena je statisti~ka analiza kako je preporu~uju Stampfer i dr. (2010) te je svakomu stroju dodijeljena opisna varijabla: Foresteri 1, Foresteri 2, Lako, Arbro, John Deer. Rezultati su statisti~ke analize prikazani u tablicama 3 i 4. Tablica 3 prikazuje rezultate deskriptivne statistike, dok tablica 4 prikazuje rezultate regresijske analize te statisti~ki zna~aj odabarnih varijabli.

Croat. j. for. eng. 33(2012)1

Productivity of Processing Hardwood from Coppice Forests (39–47)

Christian Suchomel et al.

U~inak je strojeva prikazan na slici 1, na kojoj je vidljiva ovisnost u~inaka o obujmu stabla. Najve}i je u~inak imao Foresteri 2, 109,8 m3/dan, koji je imao ve}i u~inak ~ak i od jednozahvatnoga harvestera (93,1 m3/dan). No, mora se imati na umu velik raspon snimljenih podataka za harvester, {to ostavlja mogu}nost za daljnju obradu. Iako su priklju~ene na razli~ite bagere, harvesterske glave Lako i Arbro imale su istu proizvodnost. Usporedno s izradom studija rada i vremena procjenjivan je utjecaj oblika debla na u~inak izradbe drva (slika 4), koja je obuhva}ena samo u studiji Arbro. Oblik je debla kori{ten kao nezavisna verijabla, s vrijednostima od 1 do 5 (1 – male grane i ravno deblo; 2 – debele grane ili lo{ oblik debla; 3 – debele grane i lo{ oblik debla ili vrlo debele grane; 4 – vrlo debele grane i lo{ oblik debla ili debele grane i ra{ljavo deblo; 5 – vi{e ra{lji na deblu). Ra{~lamba vremena turnusa za pojedine studije prikazana je na slici 2, gdje su radni zahvati podijeljeni kako je opisano u tablici 2. Zna~ajno je da je studija za Foresteri 1 imala najve}i udjel »ostalih radnih zahvata« zato {to se radilo o pomo}nom stovari{tu ì~are te je stroj uz osnovne zadatke morao obavljati i pomo}ne zadatke (othrpavanje istovarne rampe ì~are). Raspon jedini~nih tro{kova strojne izrade debala kretao se od 5,05 €/m3 do 18,51 €/m3 (tablica 5). Provedeno je istraìvanje dokazalo da se u kestenovim panja~ama uspje{no mogu primijeniti mehanizirane metode izradbe drvnih sortimenata, koje osiguravaju visoku proizvodnost uz niske tro{kove rada. Stoga su mehanizirane metode zadovoljavaju}a alternativa ru~no-strojnomu radu. No, ~itatelji moraju uzeti u obzir izradbu razli~itih proizvoda koji su se izra|ivali u istraìvanim studijama, {to je ve} dokazano u prija{njim istraìvanjima (Emeryat i dr. 1996, 1997, Martin i dr. 1996, Sauter i Grammel 1996, Spinelli i Spinelli 2000), te isto tako moraju uzeti u obzir kvalitetu stabala koja utje~e na proizvodnost, {to je dokazano u studiji Arbro. Nadalje, na razlike u proizvodnosti moè utjecati vje{tina operatera (Gellerstedt 2002, Purfürst 2009) jer je svakim od istraìvanih strojeva upravljao drugi operater. Iz navedenoga izlazi da se rezultati ove studije moraju tuma~iti s oprezom kako bi se izbjegli kategori~ki zaklju~ci. Klju~ne rije~i: panja~e, procesor, sortimentna metoda, studij vremena, kesten, harvester

Authors' address – Adresa autorâ: Christian Suchomel, MSc. e-mail: christian.suchomel@fobawi.uni-freiburg.de Institute of Forest Utilization and Work Science University of Freiburg Werthmannstraße 6 79085 Freiburg GERMANY

Received (Primljeno): November 10, 2010 Accepted (Prihva}eno): August 17, 2011 Croat. j. for. eng. 33(2012)1

Raffaele Spinelli, PhD. e-mail: spinelli@ivalsa.cnr.it Natascia Magagnotti, MSc. e-mail: magagnotti@ivalsa.cnr. CNR IVALSA Via Madonna del Piano 50019 Sesto Fiorentino ITALY

Original scientific paper – Izvorni znanstveni rad

Estimation of Machinery Market Size for Industrial and Energy Wood Harvesting in Leningrad Region Yuri Gerasimov, Timo Karjalainen Abstract – Nacrtak The recent and coming development of forestry practices in Northwest Russia includes fast implementation of cut-to-length (CTL) harvesting, transfer of technology, introduction of commercial thinnings and energy wood harvesting. The market size for industrial and energy wood harvesting machinery was assessed for the Leningrad region. The logging machines fleet consisted of about 700 machines for traditional tree-length technology and 120 harvesters and forwarders for CTL technology. The domestic machinery fleet is obsolete; manufacture of domestic forest machinery has dropped in both quantity and models, and thus imported CTL machinery is replacing domestic tree-length machinery. The results indicate that the market for CTL machinery could be 21 harvesters, 32 forwarders and 26 short-wood trucks per year and could increase to up to 30 – 40 machines each in the future. The maximum need for the machinery in the Leningrad region could be 50 – 60 harvesters, forwarders and short-wood trucks per year if allowable cut and commercial thinnings were realized in full scale. The market for energy wood harvesting machinery could be 4 biomass forwarders, 11 mobile chippers and 13 wood chip trucks per year and could be 6 and 15 – 20 machines per year in the future, respectively. The maximum need could be 30 – 40 biomass forwarders, mobile chippers and wood chip trucks per year. Only one third of the logging enterprises in the region had enough leased forest resources for applying the highly productive mechanized CTL technology. These 41 forest enterprises would need 270 machines, consisting of 90 harvesters, 100 forwarders and 80 short-wood trucks. Thirty-seven enterprises would need about 50 biomass forwarders and chippers and 60 wood chip trucks for energy wood harvesting. Sixty percent of the forest leasers had enough forest resources and could be users of Nordic CTL technology if allowable cut was utilized completely and if commercial thinnings were done in full scale. These 68 enterprises would need about 500 conventional logging machines, consisting of 160 harvesters, 190 forwarders and 150 short-wood trucks, and about 300 energy wood harvesting machines, consisting of 100 biomass forwarders, 100 chippers, and 110 wood chip trucks. In addition, the ten largest enterprises would need half of the total fleet. Keywords: Russia, industrial wood, energy wood, harvester, forwarder, truck, mobile chipper

1. Introduction – Uvod A remarkable growth is expected in Russian forest machine markets in the long run mainly because a thorough renewal of the current logging machines is required and because of a huge cutting potential within Russian forests. The development of using different logging methods, such as cut-to-length (CTL), full-tree (FT), and tree length (TL) method is going to have a significant influence on Croat. j. for. eng. 33(2012)1

the share between Russian forest machine markets (Karvinen at al. 2011). The Leningrad region is one of the key customers for wood harvesting machinery in Northwest Russia, as this region is one of the major producers of forest products. The total growing stock of the region is approximately 797.7 million m3, of which at least 400 million m3 is available for wood supply. Approximately 35% of the growing stock is pine, 29% spruce, 25% birch, 9% aspen and 2% other tree species.

Y. Gerasimov and T. Karjalainen

Estimation of Machinery Market Size for Industrial and Energy Wood ... (49–60)

Fig. 1 Location of the largest logging and forest industry enterprises in Leningrad region Slika 1. Polo`aj najve}ih poduze}a za izvo|enja radova pridobivanja drva i preradbu drva u Lenjingradskoj regiji About 2.1 million hectares of the region’s forests are considered to be commercial forests, where harvestable crops can be grown for timber purposes, while 2.4 million hectares are protected from harvesting based on legislation and policy. The annual allowable cut has been about 7.9 – 9.6 million m3 under bark (u.b.) in recent years; made up of 41% of coniferous and 59% of deciduous tree species. The actual harvest in 2006 was 8.2 million m3, including 5.3 million m3 from final felling, 1.4 million m3 from thinnings, and 1.5 million m3 from other fellings (Gerasimov et al. 2009, Kareliastat 2010). The region produces 4% of the industrial round wood, 13% of the pulp and paper, and 5% of the sawn timber in Russia. The forest industry contributes significantly to the Leningrad region economy. The forest industry makes up over 16% of the region’s total industrial production and employs 16% of the industrial workforce. The structure of forest industries for this region is quite diverse. There are vertically integrated holdings, including different combinations of pulp and paper mills, sawmills, and logging enterprises. There are also independent companies,

including small and medium sized enterprises, supporting companies and organizations. The forest industry collapsed in 1990 after the dissolving of the USSR, and stabilized between 1995 and 1998. There was a growing period between 1998 and 2000 due to the local currency default but there has been stagnation since 2004 in products other than lumber and fiberboards. Fig. 1 maps the key forest industry enterprises in the Leningrad region. Pulp and paper mills are located in Svetogorsk (ZAO »International Paper«), Sovetsky (OAO »Vyborgskaya tseluloza«) and Syasstroy (OAO »Syasky TsBK«). Svetogorsky P&P consumes 1.6 mill m3 u.b. of pulpwood per year, »Vyborgskaya tseluloza« 0.4 million m3 per year, and Syasky P&P 0.5 million m3 per year, respectively. The sawmill industry includes approximately 100 companies. The three largest companies produce 80% of the total sawn timber in the Leningrad region. The most important sawmills are OOO »SvirTimber« (Metsäliitto-Botnia, Podporozhye), OOO »Swedwood-Tikhvin« (IKEA, Tikhvin), OOO »Mayr-Melnhof-Holz Efimovsky« (Efimovsky). The wood-based boards industry Croat. j. for. eng. 33(2012)1

Estimation of Machinery Market Size for Industrial and Energy Wood ... (49–60)

in the Leningrad region includes fiberboard mill »Lesplitinvest« in Priozersk and particleboard mill »Zavod Nevsky Laminat« in Dubrovka. The energy wood industry in the Leningrad region includes wood pellet production. There are about 20 mills with a total capacity of over 700 thousand tons per year. Most of the forest industry capacity is concentrated in a few administrative districts with well-developed forest operations, such as Tikhvinsky, Vyborgsky, Priozorsky and Podporozhsky. The recent development of forest operations in the Leningrad region includes a fast implementation of cut-to-length (CTL) harvesting, transfer of technology, introduction of commercial thinnings and energy wood harvesting. Traditional Russian wood harvesting systems have been used side-by-side with Nordic technology. Logging enterprises in the Leningrad region play an important role in wood procurement for relatively developed forest industry in Northwest Russia. They have been among the most important suppliers of the Russian regions for the European forest industry, exporting up to 3 million m3 of industrial round wood annually (Gerasimov and Karjalainen 2006). Logging enterprises are deeply rooted in the local communities and involved in the socio-economic development of rural districts in the region. This study has been prepared as a part of the project »Possibilities for Energy Wood Procurement and Use in Northwest Russia« at the Finnish Forest Research Institute. The aim of the project was to estimate the availability of different energy wood sources as well as their technical and economic availability in the Leningrad region, to design cost effective energy wood procurement systems, and to assess needs for technology development. In this paper the machinery market size for industrial and energy harvesting was estimated.

2. Methods and data – Metode i podaci 2.1 Identification of the market – Identifikacija tr`i{ta The total global market for forest machinery is likely to be 6 000 – 8 000 machines per year, of which 3 000 could represent CTL machines (Asikainen 2005). If the logging business in Europe and Russia is mechanized rapidly and if the marketing takeover in South and North America is successful, the annual volume may rise to 10 000 machines. The total Russian market for wood harvesting machinery is approximately $150 million per year; and imports account for half of the total market (Belikov 2007). Domestic machinery production has collapsed after Croat. j. for. eng. 33(2012)1

Y. Gerasimov and T. Karjalainen

the collapse of the USSR in both quantity and models (Eremeev 2010) e.g. from over 20 000 harvesting machines per year in the Soviet time to 758 in 2008. Therefore, importing of machinery has been increasing substantially and was estimated to reach 500 machines or over 200 million Euros in the near future (Grishkovets 2006). Relief of customs duties on the imported high-tech equipment further improves opportunities to sell overseas machinery to Russia. The fleet of tree-length forest machines in Russia was estimated to be 23 000 machines including the machines imported from North America (Eremeev 2007, 2010). There are 22 enterprises producing wood harvesting and supportive equipment in Russia (Nekhamkin 2007), but the market has an oligopoly character: over 90% of the machines were produced by Onego (37%) and Altay (54%) tractor plants. There were 26 domestic models of skidders and 16 models of feller-bunchers and delimbers. Western forest machines for the full-tree method were available on the Russian market, such as John Deere and Caterpillar with 12 models of feller-buncher, skidder and delimber. However, the share of western machinery in the total Russian tree-length fleet was small; only 8% (Eremeev 2010). The traditional producer of wood harvesting machines, mostly cable skidders, for Northwest Russia and Leningrad region was Onego tractor plant. Between 1970 and 1988, Onego tractor plant produced 10 – 12 thousand skidders per year (50% of the total production in the USSR). Production dropped dramatically during the »perestroyka« period. According to Derfler et al. (2003) the average age of machines increased from 5 to 12 years between 1992 and 2000. Eighty percent of machines were utilized over a standard lifetime (Eremeev 2010). As a result, the availability rate of the machinery has decreased from 0.9 to 0.5. This means that only half of the total Russian harvesting machine fleet was in a good state, i.e. that their operating/working conditions met the common requirements. The wear rate of domestically made machines (depreciation loss) is 0.7 – 0.8. The harvesting technology has been reorganized all over Russia. The CTL method is getting more and more common due to economical, ecological and social pressures from both inside and outside of Russia. The traditional Russian wood harvesting systems are used side-by-side with Nordic technology. Nowadays in Russia more than 24% of wood is harvested with the CTL method including 18% harvested with a harvester and forwarder. The fleet of CTL technology in Russia was estimated to be 2 000 machines; mostly imported machines (Nekhamkin 2007) including about 1 000 harvesters and forwarders in Northwest Russia. The share of fully mechanized

Y. Gerasimov and T. Karjalainen

Estimation of Machinery Market Size for Industrial and Energy Wood ... (49–60)

CTL technology has been increasing since 2000. The reason was the increasing import of harvesters and forwarders mainly produced in Nordic countries. Interchangeability of harvesters and forwarders was constantly growing and machines were working in 2 – 3 shifts. Approximately 500 harvesters and forwarders were imported to Russia annually (Belikov 2007). Three manufacturers dominated on the CTL machinery market in Northwest Russia: John Deere Forestry with 55%, Ponsse with 20% and Komatsu Forestry with 16% of the total market (Belikov 2007, Nekhamkin 2007). Medium sized purpose-built machines such as John Deere Forestry (harvester 1270 and forwarders 1010/1410), Ponsse (harvesters Ergo and Beaver, forwarders Buffalo) and Komatsu Forest (harvesters Valmet 911/901, forwarder Valmet 860) were the most common CTL machinery. Light or small sized harvesters were not that common. Heavy harvesters were usually based on excavators (Volvo EC210B, Kobelco SK 135, Hitachi Zaxis 230) (Gerasimov and Sokolov 2008). Russian forest machine manufacturers have tried to design and produce domestic harvesters and forwarders, but have been unsuccessful.

2.2 Identification of the customers Identifikacija korisnika Once the key markets for wood harvesting technology in the Leningrad region were identified, the next step was to identify segments and customers that make up a large potential for forest machine sales in the region. Russian end-users of forest harvesting machines were generally logging enterprises with leased forests and in some cases contractors. Some large enterprises had wood harvesting employees within the firm. Most of the enterprises that contract out or hire wood harvesting employees were large firms that specialized in producing sawn timber, pulp and paper, or both. Due to productivity and environmental pressures, those end-users need mobile, versatile, efficient, and environmentally friendly wood harvesting machinery. Technological and environmental changes and requirements mean continuing growth and development of this market. The challenge of adhering to strict environmental regulations in the face of intense competition has increased the demand for new CTL machinery systems for wood harvesting in the region. The total number of logging enterprises officially registered in the Leningrad region was about 1 000 with over 12 000 employees (Kareliastat 2010); however, only 113 enterprises leased forests for wood supply. Harvesting operations were concentrated into large and medium-sized enterprises, which usually belong to international pulp and woodworking mills.

Fig. 2 Distribution of logging enterprises (forest leasers) based on their actual annual harvest Slika 2. Podjela poduze}a za izvo|enje radova pridobivanja drva (koncesionari {uma) s obzirom na njihov stvarni godi{nji etat The annual allowable cut of the 30 largest forest leasers was about 5 million m3 with the actual harvest of 3 million m3. The four largest logging companies accounted for the annual harvest volume of more than 200 000 m3, OAO »Svetogorsk« (International Paper) and OOO »Metsyaliitto Podporozhje« (Metsäliitto) representing the key players in pulp and paper industry. They harvested about 26% of the actual annual cut in the Leningrad region. The companies with 100 – 200 thousand m3 of harvested wood per year, i.e. OOO »Svedwood-Tikhvin« (IKEA) and ZAO »Efimovsky KLPKh« (Mayr-Melnhof-Holz), represented the largest players in sawmilling. The share of these companies was approximately 20% of the actual annual harvest in the Leningrad region. This means that only 9 key companies procured approximately half of the region’s annual harvest. The next 14 companies with 50 – 100 thousand m3 of harvested wood per year provided about 30% of the actual annual harvest in the region. Approximately 50 small companies harvested the remaining 20% of the wood (Fig. 2). Fig. 1 maps the operation areas of the largest logging enterprises in the Leningrad region. Most of the logging capacity was concentrated among a few forest districts with well developed forest industry, such as Tikhvinsky, Priozorsky and Podporozhsky.

2.3 Scenarios for the estimation of machinery market size – Scenariji za procjenu veli~ine tr`i{ta strojeva Gerasimov and Karjalainen (2011) have analyzed the development of industrial and energy wood resources based on trends in logging and woodworking in Northwest Russia including the Leningrad region. The overall development of wood procurement in the Leningrad region and woodchip proCroat. j. for. eng. 33(2012)1

Estimation of Machinery Market Size for Industrial and Energy Wood ... (49–60)

duction in particular will require a large amount of forestry machines and wood transport vehicles. The estimation of machinery market size for industrial and energy harvesting in the region was based on three scenarios (Gerasimov et al. 2007): »Actual«, »Allowable«, and »Potential«. Scenario »Actual« assumed continuing the current level of wood harvesting. It means the current utilization of annual allowable cut with a 40% use of the CTL method. The estimated potential for energy wood from logging operations was 3.5 million m3/year based on 7.9 million m3 of the actual harvest. About 2.3 million m3 was non-industrial round wood and felling residues in the cutting areas and 1.2 million m3 derived from the central processing yards. The volume harvested with CTL technology was 3.2 million m3 within 40% of the total annual cut. Scenario »Allowable« assumed increasing availability of energy wood resources based on full utilization of the annual allowable cut, utilizing the current logging technology and increasing production of sawn timber in accordance with the green-field projects, such as Svir-Timber sawmill, Mayr-Melnhof-Holz Efimovsky, etc.; see Fig. 1. The Allowable scenario means that the volume of the annually harvested stem wood in the final felling would increase from 5.1 million m3 to 9.5 million m3. It is assumed that the current proportions in logging technologies will remain the same, i.e. 40% of the CTL method, but that the share of felling by harvesters will increase from 1/3 to 2/3. The amount of energy wood

Y. Gerasimov and T. Karjalainen

available from logging could be as high as 5.3 million m3 if the entire annual allowable cut of 9.5 million m3 were utilized, if collected. About 3.3 million m3 is non-industrial round wood and felling residues in the cutting areas. The volume harvested by CTL technology is 4.9 million m3 (40% of the total allowable cut). Scenario »Potential« assumed increasing availability of energy wood due to the implementation of intensive forest management; resulting from a significant increase of commercial thinnings, full utilization of annual allowable cut with CTL technology, and increasing production of sawn timber in accordance with the available sawlog output in the region (no export). According to the Potential scenario, commercial thinnings would increase from 1.5 million m3 to 4.6 million m3 with 100% implementation of mechanized CTL technology (harvester and forwarder). The amount of energy wood available from logging could be as high as 7.2 million m3 if thinnings were also done in full scale, if collected. The assumption is that all harvesting is carried out with CTL technology, i.e. 15.3 million m3 of which 40% is from thinnings. The annual average productivity of wood harvesting machines was obtained from different statistical and companies' data in Russia and Finland (Goltsev et al. 2010a, Goltsev et al. 2010b, METLA 2010, Gerasimov et al. 2011). Assumptions about the annual productivity of CTL and energy wood harvesting machines are presented in Fig. 3.

Fig. 3 Average annual productivity of CTL industrial and energy wood harvesting machines used to estimate the machinery market size Slika 3. Prosje~na godi{nja proizvodnost strojeva za pridobivanje industrijskoga i energijskoga drva sortimentnom metodom koja se koristila za procjenu veli~ine tr`i{ta strojeva Croat. j. for. eng. 33(2012)1

Y. Gerasimov and T. Karjalainen

Estimation of Machinery Market Size for Industrial and Energy Wood ... (49–60)

Table 1 An estimation of the wood machinery fleet with three scenarios for the Leningrad region Tablica 1. Procjena broja {umskih strojeva prema trima scenarijima za Lenjingradsku regiju Source – Sredstvo Logging, mill. m3 – Drvni obujam, mil. m3 Mobile chipper, units/year – Pokretni ivera~i, kom./god. Chip trucks, units/year – Kamioni za prijevoz drvnoga iverja, kom./god. Forwarders for round wood and loose logging residues, units/year Forvarderi za oblo drvo i {umski ostatak, kom./god. Harvesters, units/year – Harvesteri, kom./god. Trucks, units/year – Kamioni, kom./god.

Scenario for harvesting round wood (RW) and energy wood (EW) Scenarij za pridobivanje obloga drva (RW) i energijskoga drva (EW) Actual – Trenutni Allowable – Dopustivo Potential – Mogu}e RW EW RW EW RW EW 3.2 2.3 4.9 3.3 15.3 7.2 – 77 – 110 – 240 – 92 – 132 – 288 93

144

451

240

28 74

– –

88 114

– –

417 356

– –

mobile chippers, 132 chip trucks and 44 forwarders for loose logging residues. The maximum theoretical need for CTL machinery in the Leningrad region could be about 400 units of forwarders, harvesters and short-wood trucks, plus about 250 units of mobile chippers, chip trucks and forwarders for loose logging residues. Table 2 shows the estimated market size for the CTL and energy wood machinery when the need to renew traditional tree-length machinery is also taken into account and replaced by CTL machinery: Þ Scenario »Actual«. Actual annual harvest is stable; a traditional technology was replaced by CTL technology according to machinery wear out; the felling process was mechanized by 1/3; forest machines were replaced every 7th year; Þ Scenario »Allowable«. Actual annual harvest grew from 7.9 to 15.3 million m3 by 5% per year; traditional technology was replaced by CTL technology according to machinery wear out; the felling process was mechanized by 2/3; forest machines were replaced every 7th year;

3. Results – Rezultati 3.1 Estimation of machinery market size for the region – Procjena veli~ine tr`i{ta strojeva za regiju Table 1 shows the CTL machinery fleet for industrial wood harvesting, which was 93 for forwarders, 28 for harvesters and 74 for short-wood trucks for the actual harvest, according to the average annual productivity. The energy wood machinery fleet for full utilization of the available energy wood resources at the cutting areas could be 77 for mobile chippers, 92 for chip trucks and 31 for forwarders for loose logging residues. If the allowable cut were realized in the Leningrad region based on the current degree of mechanization in the industrial wood harvesting, the need for CTL machinery fleet would be about 144 forwarders (+50%), 88 harvesters (+200%) and 110 short-wood trucks (+50%). The theoretical energy wood machinery fleet in the Leningrad region would be 114

Table 2 An estimation of the wood machinery fleet with three scenarios for the Leningrad region Tablica 2. Procjena veli~ine tr`i{ta {umskih strojeva prema trima scenarijima za Lenjingradsku regiju Source – Sredstvo Logging, mill. m3 – Drvni obujam, mil. m3 Mobile chipper, units/year – Pokretni ivera~i, kom./god. Chip trucks, units/year – Kamioni za prijevoz drvnoga iverja, kom./god. Forwarders for round wood and loose logging residues, units/year Forvarderi za oblo drvo i {umski ostatak, kom./god. Harvesters, units/year – Harvesteri, kom./god. Trucks, units/year – Kamioni, kom./god.

Scenario for harvesting of round wood (RW) and energy wood (EW) Scenarij za pridobivanje obloga drva (RW) i energijskoga drva (EW) Actual – Trenutni Allowable – Dopustivo Potential – Mogu}e RW EW RW EW RW EW 3.2 2.3 4.9 3.3 15.3 7.2 – 11 – 16 – 34 – 13 – 19 – 41 32

21 26

– –

30 30

– –

60 51

– –

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Estimation of Machinery Market Size for Industrial and Energy Wood ... (49–60)

Þ Scenario »Potential«. Actual annual harvest of 15.3 million m3; traditional technology was totally replaced by CTL technology; fully mechanized felling process with harvester; forest machines were replaced every 7th year. According to the Actual scenario, the use of CTL machinery would require an annual purchase of 32 forwarders, 21 harvesters and 26 short-wood trucks. The annual market for energy wood machinery could be 11 mobile chippers, 13 chip trucks and 4 forwarders for loose logging residues, if energy wood from the current logging operations were collected. If the allowable cut is realized in the Leningrad region based on the current level of mechanization, the annual market for CTL machinery could be 40 forwarders (+20%), 30 harvesters (+40%) and 30 short-wood trucks (+20%). In this case, the market for energy wood machinery in the Leningrad region could be 16 mobile chippers, 19 chip trucks and 6 forwarders for loose logging residues per year. If thinnings were also done in full scale, the market for energy wood machinery in the Leningrad region could be 50 – 60 units/yr of forwarders, harvesters and short-wood trucks, plus 30 – 40 units/yr of mobile chippers, chip trucks and forwarders for loose logging residues.

3.2 Estimation of machinery market size for logging enterprises with leased forests Procjena veli~ine tr`i{ta strojeva za poduze}a za izvo|enje radova pridobivanja drva s koncesijom nad {umama Many small size enterprises with minor leased forests are operating in the Leningrad region without financial possibilities to make investments into modern CTL technology. Therefore, it is useful to make the detailed estimation of the harvesting machinery fleets for a company level. Tables 3 – 5 show the need for CTL and energy wood machinery fleets based on assumptions in Table 1, but at the company level, i.e.: Þ Number of harvesters, forwarders and short-wood trucks (CTL machinery) and mobile chippers, biomass forwarders and chip trucks (energy wood machinery), calculated based on Actual (Table 3), Allowable (Table 4), and Potential (Table 5) scenarios in the leased forests of individual enterprises, Þ Energy wood potential of forest units of the Leningrad region where leased forests are taken into account (Gerasimov et al. 2007), Þ Data about leased forests provided by the Federal Forest Agency of Russia, Þ Whole volume harvested by fully mechanized CTL technology (using harvesters and forwarders), Croat. j. for. eng. 33(2012)1

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Þ Annual productivity of machines as presented in Fig. 3, Þ Number of machines (rounded).

Fig. 4 Number of perspective forest leasers in Leningrad region and their need for CTL machinery fleet in three scenarios Slika 4. Broj koncesionara {uma u Lenjingradskoj regiji i njihova potreba za {umskim strojevima za pridobivanje drva pri sortimentnoj metodi izrade drva prema trima scenarijima

Fig. 5 Number of perspective forest leasers in Leningrad region and their need for energy wood harvesting machinery fleet in three scenarios Slika 5. Broj koncesionara {uma u Lenjingradskoj regiji i njihova potreba za {umskim strojevima za pridobivanje energijskoga drva prema trima scenarijima 55

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Estimation of Machinery Market Size for Industrial and Energy Wood ... (49–60)

Fig. 4 shows the number of perspective forest enterprises with leased forests in the Leningrad region and their need for CTL machinery fleet in three

scenarios. Fig. 5 shows the number of perspective forest enterprises and their need for an energy wood machinery fleet.

Table 3 Estimation of the machinery fleet by forest leasers according to »Actual« scenario Tablica 3. Procjena brojnosti {umskih strojeva kod koncesionara {uma prema »trenutnom« scenariju Number of leasers AC, 1000 m3 Broj koncesionara

Harvesters Harvesteri

Forwarders Forvarderi

Timber trucks Kamioni za prijevoz drva

Biomass forwarders Mobile chippers Forvarderi za prijevoz Pokretni ivera~i {umskoga ostatka

Woodchip trucks Kamioni za prijevoz drvnoga iverja

> 200

100 – 200

50 – 99

30 – 49

Total: 41

–

AC – Actual harvest in leased area – Stvarni etat na povr{ini {uma pod koncesijom

Table 4 Estimation of the machinery fleet by forest leasers according to »Allowable« scenario Tablica 4. Procjena brojnosti {umskih strojeva kod koncesionara {uma prema »dopustivom« scenariju Number of leasers AAC, 1000 m3 Broj koncesionara

Harvesters Harvesteri

Forwarders Forvarderi

Timber trucks Kamioni za prijevoz drva

Biomass forwarders Woodchip trucks Mobile chippers Forvarderi za prijevoz Kamioni za prijevoz Pokretni ivera~i {umskoga ostatka drvnoga iverja

> 400

300 – 399

200 – 299

100 – 199

50 – 99

30 – 49

Total: 68

–

178

190

154

101

114

AAC – annual allowable cut in leased area for final fellings – Godi{nji dopustivi etat dovr{nih sje~a na povr{ini {uma pod koncesijom

Table 5 Estimation of the machinery fleet by forest leasers according to »Potential« scenario Tablica 5. Procjena brojnosti {umskih strojeva kod koncesionara {uma prema »mogu}em« scenariju Number of leasers AAC, 1000 m3 Broj koncesionara

Harvesters Harvesteri

Forwarders Forvarderi

Timber trucks Kamioni za prijevoz drva

Biomass forwarders Woodchip trucks Mobile chippers Forvarderi za prijevoz Kamioni za prijevoz Pokretni ivera~i {umskoga ostatka drvnoga iverja

> 700

600 – 699

400 – 499

300 – 399

200 – 299

100 – 199

50 – 99

30 – 49

Total: 71

–

264

284

224

152

182

AAC – annual allowable cut in leased area for final fellings and commercial thinnings – Godi{nji dopustivi etat dovr{nih sje~a i proreda na povr{ini {uma pod koncesijom

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Estimation of Machinery Market Size for Industrial and Energy Wood ... (49–60)

4. Conclusions – Zaklju~ci The results indicated that the annual market for CTL machinery in the Leningrad region can be approximately 20 – 30 medium sized purpose-built harvesters/forwarders and short-wood trucks, respectively. The market could be 30 – 40 units per year in the future, if the allowable cut were utilized or even 50 – 60 harvesters, forwarders and short-wood trucks per year, if commercial thinnings were also done on a full scale. The current market for energy wood machinery can be approximately 4 biomass forwarders, 10 mobile chippers and wood chip trucks per year. The market could be about 15 – 20 units per year in the future, if allowable cut were utilized or 30 – 40 biomass forwarders and mobile chippers per year, if commercial thinnings were also done on a full scale. The total number of enterprises registered for wood harvesting operations in the Leningrad region was about one thousand, but only one hundred enterprises had leased forests and could be taken into account as major customers of CTL machinery manufacturers. Only one third of the current forest leasers in the Leningrad region had enough leased forest resources and could be the users of fully mechanized CTL technology based on the Actual scenario. These 41 enterprises needed 270 CTL machines altogether – 90 harvesters, 100 forwarders and 80 trucks. Thirty-seven companies needed 50 chippers, 50 biomass forwarders, and 60 woodchip trucks for energy wood harvesting. The share of the 10 largest enterprises would be half of the total fleet. Sixty percent of forest leasers in the Leningrad region had enough leased forest resources and could be the users of fully mechanized CTL technology based on the Allowable scenario. These 68 enterprises needed 500 CTL machines altogether – 160 harvesters, 190 forwarders and 150 trucks. Fifty-six companies needed 100 chippers, 100 biomass forwarders, and 110 woodchip trucks for energy wood harvesting. The share of the 10 largest enterprises would be half of the total fleet. Sixty percent of the current forest leasers in the Leningrad region had enough leased forest resources and could be the users of fully mechanized CTL technology based on the Potential scenario. These 71 enterprises would need 770 CTL machines altogether – 260 harvesters, 280 forwarders and 230 trucks. Seventy companies would need 150 chippers, 150 biomass forwarders, and 180 woodchip trucks for energy wood harvesting. The wood harvesting machinery fleet in the Leningrad region was estimated at about 700 logging machines for the traditional tree-length technology Croat. j. for. eng. 33(2012)1

Y. Gerasimov and T. Karjalainen

and approximately 120 harvesters and forwarders for CTL technology. In the Leningrad region the fleet of domestic logging machinery was obsolete; the wear rate of fixed assets was about 50% and needs an improvement. The actual harvest in the Leningrad region has been about 8 million m3 in recent years and may not increase in the near future. This study presented the most recent publicly available official governmental statistical data on wood harvesting and forest leasing in the Leningrad region in 2006. However, the actual harvest volume is not a constant for various reasons. In the period 2008 – 2010, the actual harvest volume slightly decreased due to challenges in implementation of the new Forest Code, increasing custom duties for round wood export, the financial crisis of 2008 and environmental impacts (Gerasimov and Karjalainen 2008, Karvinen et al. 2011). The same statement is true for the annual allowable cut. Nevertheless, considering that the scenario of forest use can have variants, the methodology of using the techniques described in this study gives some flexibility for determining the need for harvesting machines. The wood harvesting industry in Northwest Russia continues at the Onego tractor plant with the production of two models of traditional caterpillar skidders, but the production dropped in 1988 from 12 000 to 100 machines per year. The imported CTL machinery is replacing domestic tree-length machinery supporting the recent development of forestry practices in the Leningrad region including fast implementation of CTL harvesting, transfer of technology, introduction of commercial thinnings and energy wood harvesting. The economic indexes of technology development in wood harvesting showed positive signs, as the renewal rate for harvesting machinery has been increasing since 2005 from 14% (2005) to 36% (2009) (Kareliastat 2010). This means that logging enterprises are now in a better position to renew machinery and technology than in the past. Nowadays there are also better possibilities to finance the purchase of new technology. This means that the methodology, presented in the study, is timely and able to support the development of strategies, concepts and programs related to the forestry mechanization in both the Leningrad region and other regions of Russia.

Acknowledgements – Zahvala The work was carried out for the project »Wood Harvesting and Logistics«, financed by the European Union through the Finnish Funding Agency for Technology and Innovation (TEKES).

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5. References – Literatura Asikainen, A., Ala-Fossi, A., Visala, A., Pulkkinen, P., 2005: Metsateknologiasektorin visio ja tiekartta vuoteen 2020 (Forest technology vision and roadmap for 2020). Working Papers of the Finnish Forest Research Institute 8, 92 p. Belikov, D., 2007: Tehnika stvola (Stem techniques). Business Guide 70(3646): 35–36. Derfler, A. A., Bykov, V. V., Golubev, I. G., 2003: Osnovnxe Napravleniq Tehni~eskoj Politiki OAO Alttrak

(Main directions of technological policy of OAO Alttrak). Timber Industry 2: 25–28.

Eremeev, N. S., 2007: Po~emu neobhodimo sohranenie i razvitie ote~estvennogo lesnogo ma{inostroeniq (Why necessary to safe and develop the manufacture of domestic forest machinery). Forest Business 5: 56–58. Eremeev, N. S., 2010: Lesnxe ma{inx iz Rossii vpolne mogut bxty konkurentosposobnxmi na mirovom rxnke (Forest machines from Russia can be quite competitive on the world market). Special Machinery 3: 56–58. METLA, 2010: Statistical Year Book of Finnish Forestry. Helsinki: Finnish Forest Research Institute. 470 p. Gerasimov, Y., Karvinen, S., Leinonen, T., 2009: Atlas of the forest sector in Northwest Russia 2009. Working Papers of the Finnish Forest Research Institute 131, 43 p. Gerasimov, Y., Karjalainen, T., 2006: Development of wood procurement in Northwest Russia: Round wood balance and unreported flows. European Journal of Forest Research 125(2): 189–199. Gerasimov, Y., Karjalainen T., 2008: Development program for improving wood procurement in Northwest Russia based on SWOT analysis. Baltic Forestry 14(1): 85–90. Gerasimov, Y., Karjalainen, T., 2011: Energy wood resources in Northwest Russia. Biomass Bioenergy 35(5): 1655–1662.

Gerasimov, Y., Karjalainen, T., Ilavský, J., Tahvanainen, T., Goltsev, V., 2007: Possibilities for energy wood procurement in north-west Russia: Assessment of energy wood resources in the Leningrad region. Scand. J. For. Res. 22(6): 559–567. Gerasimov, Y., Senkin, V., Väätäinen, K. 2011. Productivity of single-grip harvesters in clear-cutting operations in the northern European part of Russia. European Journal of Forest Research. DOI: 10.1007/s10342-011-0538-9. 8 p. Gerasimov, Y., Sokolov, A., 2008: Ergonomic characterization of harvesting work in Karelia. Croatian Journal of Forest Engineering 30(2): 159–170. Goltsev, V, Ilavský, J, Gerasimov, Y, Karjalainen, T., 2010: Potential for biofuel development in Tihvin and Boksitogorsk districts of the Leningrad region – The analysis of energy wood supply systems and costs. Forest Policy and Economics 12(4): 308–316. Goltsev, V., Ilavský, J., Karjalainen, T., Gerasimov Y., 2010: Potential of energy wood resources and technologies for their supply in Tihvin and Boksitogorsk districts of the Leningrad region. Biomass and Bioenergy 34(10): 1440–1448. Grishkovets, E., 2006: Topornaq rabota (Clumsy work). Business Guide 194(3525): 36–37. Kareliastat, 2010: Lesopromx{lennxj kompleks regionov Severo-Zapadnogo Federalynogo okruga Rossii (Forest Sector of Northwest Russian regions). Petrozavodsk, 212 p. Karvinen, S., Välkky, E., Gerasimov, Y., Dobrovolsky, A., 2011: Northwest Russian Forest Sector in a Nutshell. Metla, Joensuu, 144 p. Nekhamkin, V., 2007: Celesoobraznosty primeneniq zarube`noj lesozagotovitelynoj tehniki (Advisa-

bility of import wood harvesting machinery utilization). Forest Business 2 (2007): 60–63.

Sa`etak

Procjena veli~ine trì{ta strojeva za pridobivanje industrijskoga i energijskoga drva u Lenjingradskoj regiji Lenjingradska je regija jedna od najve}ih proizvo|a~a {umskih proizvoda u Rusiji te je stoga najve}e trì{te {umskih strojeva za pridobivanje drva. Ukupna je drvna zaliha u regiji oko 797,7 milijuna m3. Godi{nji dopu{teni sje~ivi etat je oko 7,9 – 9,6 milijuna m3, od ~ega na crnogori~ne vrste drva otpada 41 %, a na bjelogori~ne vrste drva 59 % etata. Stvarni sje~ivi etat u 2006. iznosio je 8,2 milijuna m3, od toga 5,3 milijuna m3 iz dovr{nih sje~a, 1,4 milijuna m3 iz proreda te 1,5 milijuna m3 iz ostalih vrsta sje~a (Gerasimov i dr. 2009, Kareliastat 2010). Regija proizvodi 4 % industrijskoga obloga drva, 13 % celuloze i papira i 5 % od piljene gra|e u Rusiji. Poduze}a, koja se bave pridobivanjem drva, godi{nje izvezu 3 milijuna m3 te stoga imaju zna~ajnu ulogu na drvnu industriju u sjeverozapadnoj Rusiji i na europsku drvnu industriju (Gerasimov i Karjalainen 2006). [umarstvo i drvna industrija Lenjingradaske regije ~ine vi{e od 16 % ukupne industrijske proizvodnje i zapo{ljavaju 16 % radne snage. Zbog potrebe za obnovom {umske mehanizacije te zbog golemih mogu}nosti ruskih {uma o~ekuje se velik rast trì{ta {umskih strojeva. Razlike izme|u metoda izrade drva (sortimentna, stablovna, deblovna metoda) imat }e zna~ajan utjecaj na raspodjelu trì{ta {umskih strojeva u Rusiji.

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Daljnji razvoj sustava pridobivanja drva u Lenjingradskoj regiji razumijeva uvo|enje sortimentne metode izrade drva i komercijalnih proreda te ve}e pridobivanje energijskoga drva. Usporedno s novim sustavima primjenjuju se i tradicionalne metode pridobivanja drva. Na svjetskom trì{tu {umskih strojeva i opreme godi{nje se proda 6000 – 8000 strojeva, od ~ega 3000 otpada na strojeve koji se koriste pri sortimentnoj metodi izrade drva (Asikainen 2005). Ako se nastavi ubrzano mehaniziranje {umskih radova u Europi i Rusiji, te ako se trì{tu pridodaju Sjeverna i Ju`na Amerika, godi{nje bi se moglo prodavati i do 10 000 {umskih strojeva. U Rusiji se godi{nje tro{i oko $150 milijuna eura na kupovinu {umskih strojeva, a polovica te vrijednosti otpada na uvoz (Belikov 2007). Doma}a industrija {umskih strojeva i opreme naglo je propala raspadom SSSR-a – proizvodnja je pala s 20 000 proizvedenih strojeva godi{nje na samo 758 strojeva u 2008. godini. Stoga je uvoz bitno rastao te se procjenjuje da bi mogao dose}i vrijednost od 200 milijuna eura/god. odnosno 500 strojeva/god. (Grishkovets 2006). Procjenjuje se da sada u Rusiji ima 23 000 {umskih strojeva, uklju~uju}i uvezene strojeve iz Sjeverne Amerike koji su ve}inom prilago|eni za deblovnu metodu izrade drva (Eremeev 2007, 2010). Prema Derfleru i dr. (2003) strojevi imaju prosje~no izme|u 5 i 12 godina. Osamdeset posto strojeva koristi se dulje od amortizacijskoga roka (Eremeev 2010). Krajnji su korisnici {umskih strojeva uglavnom poduze}a koja imaju koncesiju nad {umama ili privatni izvo|a~i radova. Zbog potrebe za pove}anjem proizvodnosti i stroìh ekolo{kih propisa pove}ava se potreba za raznovrsnijim, u~inkovitijim i okoli{no pogodnijim {umskim strojevima. Zbog toga u posljednje vrijeme sortimentna metoda izrade drva postaje sve u~estalija. Procjenjuje se da u primjeni sortimentne metode izrade drva u Rusiji ima 2000 ve}inom uvezenih strojeva. Njihov je broj od 2000. godine u stalnom porastu te se procjenjuje da se danas u Rusiju uveze oko 500 harvestera i forvardera na godinu. Za potrebe procjene veli~ine trì{ta {umskih strojeva u ovom su radu postavljena tri scenarija: »trenutni«, »dopustivi« i »mogu}i«. Þ »Trenutni« se scenarij zasniva na postoje}em stupnju pridobivanja drva, tj. na godi{njem etatu od 7,9 mil. m3/godi{nje od ~ega se 40 % etata izra|uje sortimentnom metodom, a 3,5 mil. m3 odnosi se na energijsko drvo. Þ »Dopustivi« se scenarij temelji na pove}anju pridobivanja energijskoga drva te time pove}anju godi{njega etata na 9,5 mil. m3, a da se 40 % etata izra|uje sortimentnom metodom uz ve}u uporabu harvestera. Þ »Mogu}i« se scenarij temelji na primjeni isklju~ivo sortimentne metode izrade drva i pove}anju koli~ine drva iz proreda, {to }e rezultirati godi{njim etatom od 15 milijuna m3 (od ~ega bi 40 % etata trebalo biti iz proreda, odnosno 7,2 mil. m3 energijskoga drva). Proizvodnost strojeva s kojom su ra|ene procjene dobivena je iz raznih statisti~kih podataka te iz podataka koje su ustupila {umarska poduze}a iz Rusije i Finske (slika 3). U tablici 1 prikazane su potrebe za {umskim strojevima prema svim trima predloènim scenarijima. Najve}i mogu}i broj strojeva za rad pri sortimentnoj metodi izrade drva procjenjuje se na 400 forvardera te isto toliko harvestera i kamionskih skupova za prijevoz drva, te dodatno po 250 komada pokretnih ivera~a, forvardera i kamiona za privla~enje i prijevoz drvnoga ostatka. Tablica 2 tako|er prikazuje potrebu za {umskim strojevima prema svim trima predloènim scenarijima kada se uzme u obzir zamjena starih strojeva za rad pri stablovnoj metodi izrade drva s nabavom novih strojeva za primjenu sortimentne metode izrade drva te uz zamjenu strojeva svakih 7 godina. U tablicama 3 – 5, na temelju procjena iz tablice 1, prikazane su potrebe poduze}a (koncesionara {uma) za {umskom mehanizacijom. Rezultati pokazuju da je godi{nja potreba za {umskom mehanizacijom u Lenjingradskoj regiji izme|u 20 – 30 komada srednje velikih forvardera, harvestera i kamiona za prijevoz drva. Potreba bi se u budu}nosti mogla pove}ati na 30 – 40 strojeva godi{nje, ako se sije~e planirani godi{nji etat ili ~ak 50 – 60 strojeva godi{nje ako se intenzivno provode prorede. U proizvodnji energijskoga drva sada{nja je potreba 4 forvardera, 10 ivera~a i 10 kamiona za prijevoz drvnoga iverja. Kada bi se izvr{io planirani etat i kada bi se provodile intenzivne prorede, potreba za strojevima iznosila bi 30 – 40 strojeva godi{nje. Od pribli`no tisu}u poduze}a, koja se bave poslovima u {umarstvu, samo njih stotinu imaju koncesiju na {umama te dovoljno sredstava za nabavu nove mehanizacije i primjenu sortimentne metode. Samo tre}ina koncesionara ima mogu}nosti za potpunu primjenu sortimentne metode izrade drva. Njihova je potreba prema »trenutnom« scenariju 270 strojeva: 90 harvestera, 100 forvardera, 80 kamiona za prijevoz drva. Samo se 37 poduze}a bavi proizvodnjom energijskoga drva i imaju potrebu za 50 ivera~a, 50 forvardera i 60 kamiona za prijevoz drvnoga iverja. Prema »dopustivom« scenariju 60 % koncesionara {uma ima dovoljnu povr{inu {uma i u mogu}nosti je potpuno primijeniti sortimentnu metodu izrade drva. Njihova potreba za {umskim strojevima ogledala bi se u 160 harve-

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Estimation of Machinery Market Size for Industrial and Energy Wood ... (49–60)

stera, 190 forvardera i 150 kamiona za prijevoz drva. Ukupno 56 poduze}a koja se bave proizvodnjom energijskoga drva imalo bi potrebu za 100 ivera~a, 100 forvardera i 110 kamiona za prijevoz drvnoga iverja. Prema »mogu}em« scenariju 60 % koncesionara {uma, uz dovoljnu povr{inu {uma i potpunu primjenu sortimentne metode izrade drva, imalo bi potrebu za 260 harvestera, 280 forvardera i 230 kamiona za prijevoz drva. Broj poduze}a koja se bave proizvodnjom energijskoga drva pove}ao bi se na 70, a imali bi potrebu za 150 ivera~a, 150 forvardera i 180 kamiona za prijevoz drvnoga iverja. Ekonomski pokazatelji u tehnolo{kom razvoju pridobivanja drva pokazuju pozitivne rezultate kako se od 2005. godine sve vi{e obnavlja {umska mehanizacija u Rusiji. Iz toga se zaklju~uje da se metode opisane u radu mogu koristiti kao podloga za razvoj nabavnih strategija i programa {umske mehanizacije i u Lenjingradskoj regiji i u ostatku Rusije. Klju~ne rije~i: Rusija, industrijsko drvo, energijsko drvo, harvester, forvarder, kamion, pokretni ivera~

Authors' address – Adresa autorâ:

Received (Primljeno): July 21, 2011 Accepted (Prihva}eno): January 09, 2012

Yuri Gerasimov, PhD. e-mail: yuri.gerasimov@metla.fi Prof. Timo Karjalainen, PhD. e-mail: timo.karjalainen@metla.fi Joensuu Research Centre Finnish Forest Research Institute Yliopistokatu 6 Box 68 FIN-80101 Joensuu FINLAND Croat. j. for. eng. 33(2012)1

Original scientific paper – Izvorni znanstveni rad

Productivity Models for Operational Planning of Timber Forwarding in Croatia Igor Stanki}, Tomislav Por{insky, @eljko Toma{i}, Ivica Tonkovi}, Marko Frnti} Abstract – Nacrtak In the area of Croatian lowland forests, forwarders are usually used for extraction of timber assortments. Within the project »Systematization of norms for the production of timber assortments«, which was financed by the state company »Hrvatske {ume« d.o.o. (»Croatian Forests«), the process of development and implementation of new productivity norms for forwarders was carried out. Initially, for the execution of the research, it was necessary to gather data about technical characteristics of forwarders most frequently used in Croatia, but also around the world. The morphological analysis was performed and it was the basis for the classification of forwarders into classes. Three classes of forwarders were obtained after cluster analysis and load capacity appeared to be the most important factor. Machine performance was evaluated on 30 research sites. The standard method of time study (snap-back chronometric technique) was used. During the recording process, data of factors influencing forwarding (stand and terrain conditions) were collected. After analyzing the collected data, it was determined that the forwarding productivity depends on the forwarder class, average extraction distance, load characteristics, terrain and stand conditions. Regression analysis was used for identifying the time consumption of individual work components, and the productivity model for forwarding was developed. The obtained model was implemented into the application HsPPI. This is a part of the information system developed by IT Department of the state enterprise »Hrvatske {ume« d.o.o. and is used for production planning in timber harvesting. The system is based on dBase IV databases and two main program modules. The main parts of the system are: tree marking data, assortment structure plan, production plan (felling, processing and extraction) and sales plan. Within a part of the production plan there is a module for calculating productivity norms for timber forwarding. Keywords: forwarder; productivity norms; planning; lowland forests, Croatia

1. Introduction – Uvod In the Republic of Croatia, state forests and forestland cover an area of 2,106,917 ha and most of them (96%) are managed by the state enterprise »Hrvatske {ume« d.o.o. (»Croatian Forests«; H[; Anon 2006). From the economic aspect, selection and even-aged forests are the most significant forests of high silvicultural form. In the Republic of Croatia timber extraction is mainly mechanized, while felling and processing is motor-manual and carried out by chainsaws (Bojanin and Krpan 1997). In Croatian mountainous selection forests, skidders are used for timber extraction (Sabo and Por{insky 2005). On the other hand, in cases of even-aged forests in hilly and lowland Croat. j. for. eng. 33(2012)1

areas, depending on the stand and terrain conditions, skidders and forwarders are used for timber extraction, while the use of adapted farming tractors and tractor assemblies has decreased (Krpan 1996; Beuk et al. 2007). The lowland area of forests and forestland owned by the state amounts to something more than 322 thousand ha (Pentek et al. 2011). The lowland forests are of particular importance for this research, as forwarders are mainly used in this part of Croatia. Lowland forests consist of forest stands of the pedunculate oak (Quercus robur L.), narrow-leaved ash (Fraxinus angustifolia Vahl.), black alder (Alnus glutinosa [L.] Gaertn.), willows (Salix sp.), poplars (Populus alba L., Populus x euramericana clones) and common hornbeam (Carpinus betulus L.). Annual removal

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amounts to more than 1 mill m³ of wood (Anon 2011). The figures might not be impressive; however, wood from these forests (pedunculate oak) has been achieving high prices on the roundwood market, which is where the importance of the lowland forests can be seen at its best. The aim of this research is to establish the system of planning timber extraction from late thinning and shelterwood felling of lowland forests in Croatia.

2. Problematics – Problematika Forwarders are self-propelled vehicles intended for the transport of trees and their parts loaded in the vehicle bunk area (ISO 2009). The development of the first forwarder started in Sweden around 1950s, and their use in Croatia started in 1971 (Slabak 1983). Forwarders were originally used in cut-to-length timber harvesting, where the felling of trees was performed by harvester, and extracting by forwarder. In Croatian forestry forwarders are mostly used in lowland forests, particularly for the extraction of timber from shelterwood felling and late thinning (Por{insky 2002). Therefore, for investigating forwarders’ performance in Croatia, the lowland forests are the most significant as they cover almost 25% of the total area covered with high forests (Krpan 1996). Secondary (technical) productivity in forestry is significant for the research of forest operations (Löffler 1989). From a scientific point of view, the research of forest operations includes the study of timber harvesting, ergonomics, mechanization, construction, economic aspect and planning of operations, all within the framework of a sustainable forestry development (Samset 1992). The research of forestry operations, and hence also timber forwarding, is based on time study and on monitoring the influencing (quality and quantity) factors, data analysis, and mathematical modeling of time consumption of individual components of the working process (Samset 1990). Similarly as other forms of timber extraction, forwarding also has the characteristics of a cyclic working process. Forwarder efficiency is affected by numerous factors. The most important factors influencing the efficiency of timber forwarding is the travel distance (Sever 1988). With the increase of the travel distance, the impact of the load volume on the vehicle productivity is also increased (Raymond 1989). Apart from the forwarding distance, productivity is also affected by the average assortment volume (number of pieces in the load) and quantity of timber on a felling site, which is more pronounced in thinning stands (Tufts and Brinker 1993; Tufts 1997). The highest share of time consumption in forwarder operations is related to the so-called terminal times, and namely loading and unloading of timber (Minette et al. 2004).

Optimization of load volume and forwarding distance, and giving preference to downhill forwarding are the key factors for improving the productivity of forwarders (Tiernan et al. 2004). Terrain slope higher than 30% considerably decreases the productivity of forwarders because on such terrains vehicle mobility is limited (Zimbalatti and Proto 2010). Terrain classification aimed at determining the optimum machine for timber extraction shows that in hilly-mountainous area, too, the share of timber forwarding is quite considerable (Miheli~ and Kr~ 2008; Pentek et al. 2008). On steep terrain, up to 60%, it is possible to use forwarders with winch, the so-called cable forwarders (Kühmaier and Stampfer 2010). The use of semi-tracks in conditions of limited soil bearing strength increases fuel consumption but provides vehicle mobility (Wästerlund et al. 2011). Apart from travel distance, load volume and terrain conditions, forwarder productivity is also affected by the type of felling, length and type of assortment, driver’s skill and knowledge, as well as characteristics of hydraulic crane and vehicle load space (White 2004). The increase of the average assortment volume and terrain slope in travel direction (downhill forwarding) result in the decrease of time consumption (Ghaffarian et al. 2006). The density of secondary forest roads (forest trails) also affects the forwarding productivity (Mederski 2006). Up to date planning methods, i.e. spatial optimization of working cycle shifts based on data on quantity and locations of assortments and possible travel areas of the felling site also increase the timber forwarding productivity (Flisberg et al. 2007). Comparative research of skidding/forwarding machines carried out in stands of small coniferous trees showed that, in terms of costs, figures speak in favour of timber forwarding, as forwarder productivity is twice higher than the productivity of the skidder with winch (Li et al. 2006). Forwarder efficiency depends on the type of the vehicle used, i.e. on its nominal carrying capacity, as forwarders of higher carrying capacity achieve lower costs and higher productivity per product unit (Jirou{ek et al. 2007). Nowadays forwarders are not conceptually different from those of half a century ago, but they have made serious progress in terms of environmental soundness, ergonomics and steering automation (Pandur et al. 2009). One of the ways to increase productivity is the use of dynamic system for changing the volume of the bunk area (Brunberg 1999), i.e. its height and width (Brunberg 2001). Attaching the trailer with the loading space behind the rear end of the standard forwarder may increase the system productivity (Lindroos and Wasterlund 2011). Investigations were performed of the use of »flats« or »swop bodies«, where timber is not unloaded Croat. j. for. eng. 33(2012)1

Productivity Models for Operational Planning of Timber Forwarding in Croatia (61–78)

from the forwarder nor loaded into the truck, as they are used with both kinds of transport, thus increasing productivity and simplifying primary transport of timber, but with increased costs (Freitag and Warkotsch 2011). Considering the productivity and costs of timber harvesting machines at an annual level, the share of the travel of machines between felling units is quite considerable, so when planning, the possibility of leasing trucks for the transport of machines should be taken into account (Väätäinen et al. 2006). Productivity of timber forwarding is higher than the productivity of timber skidding in lowland forests of Croatia, and the increase depends on stand and terrain conditions and ranges between 28 and 126% (Bojanin and Krpan 1994). The operation of forwarders in Croatia, unlike the Scandinavian assortment method (CTL), makes no use of felling and processing machines. This is the effect of natural factors (natural forests, trees of large size, considerable share of broadleaved trees, etc.), but also of tradition (Bojanin and Krpan 1997). The above said is the cause of a different approach to gathering and processing data, selecting the influencing factors and modelling the working process. One of the problems arising is the definition and determination of the mean distance of timber forwarding. Some authors consider that the distance of timber forwarding is the distance between the roadside landing and the point in the felling site when the bunk area is half loaded with timber (Kuitto et al. 1994; Nurminen et al. 2006). Accordingly, the mean distance of timber forwarding would be equal to the sum of travel distance of unloaded vehicle and half the travel in timber loading i.e. the travel between the loading points (Suvinen 2006; Väkevä et al. 2001). When investigating forwarders in Croatian lowland forests, the distance of timber forwarding was considered to be the arithmetic mean of the sum of distances tra-

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velled by fully loaded and unloaded forwarder, while the time consumption of the vehicle movement during loading process was defined depending on felling density, i.e. net timber volume per hectare (Por{insky 2002, 2005; Stanki} 2010). The production of timber assortments has been supported by information systems used by the state company H[ for monitoring and recording the production of timber assortments. The information system has been continuously developing for twenty years, since the founding of the company, and it is the result of the development program of the company’s IT Department. At the beginning of the development, the system was based on personal computers with programs made in computer language FoxPro 2.6 for DOS (dBase IV as database). Although the computerization of the company has gone a long way from those times, a part of these programs and FoxPro2.6 as program language are still being used, while new programs are being developed for Windows operating systems in Visual FoxPro 9.0 and on.NET platform with MS SQL database. A part of the information system of the company H[ is the production subsystem, by which all timber harvesting processes are monitored – from production planning to issuing bills to buyers. HsPPI and HsPro are important parts of this subsystem. HsPPI refers to the production planning, while HsPro refers to the monitoring of timber assortments production. The basis of the information flow is in the forest database HsFond that basically represents digitalized Management Plan Prescriptions. One of the factors is the Harvesting Plan, which represents the beginning of the production planning. On that basis, the harvesting (sub)compartment is selected, tree marking data is prepared, distribution of marked trees is entered, harvest is planned out, cut block is established, the technology of timber processing is chosen along with the production plans, where the felling and processing norms, as well as the primary transport, have to be determined. At the end of the planning process, the sales plan is developed. All these processes are carried out within the HsPPI application that H[ uses for the preparation of production within harvesting.

3. Materials and methods – Materijal i metode 3.1 Classification of forwarders – Razredba forvardera

Fig. 1 Forwarding in Croatian lowland forests Slika 1. Izvo`enje drva u hrvatskim nizinskim {umama Croat. j. for. eng. 33(2012)1

A good knowledge of forwarders as means of work in the forestry production is of crucial significance. Many research methods are already known,

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Table 1 Some technical features of investigated forwarders Tablica 1. Neke tehni~ke zna~ajke istra`ivanih forvardera Forwarder type Tip forvardera

Number of wheels Broj kota~a

Engine power Snaga motora

Length Duljina

Width [irina

Height Visina

Mass Masa

Payload Nosivost

Crane reach Dohvat dizalice

Timberjack 1210

114

9,060

2,640

3,710

11,720

12,000

10.3

Timberjack 1410B

9,205

2,705

3,700

16,500

14,000

8.5

Timberjack 1710B Valmet 840

129 156.5

10,450

3,010

3,900

17,400

17,000

7.2

124

9,007

2,650

3,780

13,800

12,000

9.2

Valmet 860

140

9,170

2,740

3,789

14,300

14,000

9.2

from those that determine borderline usability, to those that study the historical development of its construction. One of the studying methods for the machines used in forestry is the morphological analysis based on the selected geometrical, mass and other factors, on which basis dependencies are calculated and opinion on validity of machine selection is made (Por{insky 1997). One of the first morphological analyses of off-road vehicles was carried out by Bekker in 1956 (Sever 1980). Gradually, the method was accepted and is used even today for the evaluation of forestry machines or tools, especially by researchers from Department of forest engineering of the Forestry Faculty Zagreb for investigation of chippers ([u{njar 1998), farming tractors (Horvat and [u{njar 2001), skidders (Horvat et al. 2007), hydraulic cranes ([u{njar et al. 2007), chainsaws (Por{insky et al. 2008), farmer winches ([u{njar and Bori} 2008). In the Croatian forestry, the following forwarders are used most frequently: Timberjack 1210, Timberjack 1410, Timberjack 1710, Valmet 840 and Valmet 860 (Table 1). Modeling of productivity individually for each forwarder would be cost-ineffective, so it was necessary to group them in classes and analyze them on that basis. Many forwarder classifications are already known, and according to them forwarders are classified by net mass, load capacity or gross mass (vehicle + load, (Por{insky 1997)). The latest forwarder classification found in literature is made based on their loading capacity (payload) to light (<10 t), medium (10 t – 14 t) and heavy forwarders with the load capacity over 14 t (Brunberg 2004). In this case, the morphological analysis of forwarder families according to their numerical values (dimensions, mass, load capacity, etc.) will be used as a basis for grouping vehicles in classes. The data have taken from the obtained and adapted database, only for the vehicles of the new generation (Lugmayr et al. 2009).

3.2 Assortments characteristics – Zna~ajke sortimenata The Croatian lowland forests are characterized by a great variety of stand conditions. There is a wide range of tree species, from willows and poplars, over black alder and narrow-leaved ash, to pedunculate oak and common hornbeam. The area is characteristic by the assortment method of processing, with forwarding as a special way of timber extraction. The assortment volume is important for obtaining the correct figures of the mean load volume that impact the forwarder productivity. The aim was to obtain the mean assortment dimension, so it was formed on the basis of trees taken from the tree marking data, that is by connecting the data from two applications of the information production subsystem HsPPI and HsPro. Data on trees marked to be felled and data on processed timber assortments in the work yards were collected for the yards where the extraction has been carried out with forwarders over the last couple of years (Fig. 2). Data on tree species whose share in the lowlands is low (fruit trees, common maple, lowland elm, walnut, etc.) were left out from the analysis, as well as cutting blocks with small number of samples. Only the data for the most important species, based on their share in the prescribed removal of the Croatian lowland forests, were taken into analysis: pedunculate oak, common hornbeam, narrow-leaved ash and black alder. The goal of the analysis is to determine the mean assortment volume, mean diameter and length from the volume of marked tree by the tree species. The stated is necessary to determine the productivity of forwarders in this system of harvesting.

3.3 Forwarder productivity – Proizvodnost forvardera The research of forwarder productivity was carried out in the area of Croatian lowland forests (Fig. 2). In this research, the term Object of Study (OS) is Croat. j. for. eng. 33(2012)1

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Fig. 2 Research sites of forwarder productivity and timber assortments characteristics Slika 2. Mjesta istra`ivanja proizvodnosti forvardera i zna~ajki sortimenata used, which refers to individual stand, that is the compartment/subcompartment where harvesting is carried out. Raw data for productivity analysis were taken from the previous investigations of a total of 30 objects; 5 OS (Por{insky 2000) + 3 OS (Por{insky 2005) + 22 OS (Stanki} 2010). Average removal per OS was 199.79 m3/ha, average tree size was 3.22 m3/tree and average area of OS was 27.70 ha. The research of the machine work is based on the time and work study. The basis is the work and time study, division of work process or work phase into consisting parts of the shortest possible time duration that can still be measured precisely enough. Contemporary approach to time study presupposes the implementation of analytical measuring methods, whereby work process is divided under particular schemes into work components with the goal of synthesis during data and results processing. Extraction of timber by forwarders has the characteristics of cyclic work. Each cycle (turn) consists of four main cyclic work components (unloaded traveling, timber loading, loaded traveling and unloading of timber), plus work pauses or time consumptions whose character is not cyclic, but periodic. Forwarder productivity is modeled by the following module: Croat. j. for. eng. 33(2012)1

ìï t = fa í sof ïî

ü æ 60 60 ö æ ö ÷ + son × ç 60 + 60 ÷ + tl + tu ïý é min ù × çç + ÷ ç ÷ ïþ êë turn úû è v1 v2 ø è v3 v4 ø P=

60 × Vl ém 3 ù ê ú t ë h û

where: t – total time, min/turn sof – forwarding distance (offroad), km v1 – unloaded vehicle speed (offroad), km/h v2 – loaded vehicle speed (offroad), km/h son – forwarding distance (forest road), km v3 – unloaded vehicle speed (forest road), km/h v4 – loaded vehicle speed (forest road), km/h tl – loading time, min/turn (tl=tl1+tl2) tu – unloading time, min/turn (tu=tu1+tu2) fa – additional time factor Vl – load volume, m3/turn P – productivity, m3/h The study of forwarder work time was carried out by snapback method, using manual digital chronometer. Besides the time study, data were collected of all factors influencing the work process. Forwarding distance was measured by hand GPS devices. In order to establish the forwarder performance, loaded

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Productivity Models for Operational Planning of Timber Forwarding in Croatia (61–78)

Table 2 Correlation table of studied values (those bold are significant at p < 0.05) Tablica 2. Korelacijska tablica prou~avanih vrijednosti (podebljane su signifikantne za p < 0,05) Characteristics Zna~ajke

Means Std. Dev. Artimeti~ke Standardne sredine devijacije

Engine power Snaga motora

Length Duljina

Width [irina

Height Visina

Clearance Odignutost vozila od podloge

Mass Masa

Payload Nosivost

Crane reach Doseg dizalice

Lifting moment (gross) Bruto podizni moment dizalice

Engine power, kW Snaga motora, kW

138.24

28.51

1.00

0.60

0.72

0.53

0.82

0.81

0.08

0.79

Length, mm Duljina, mm

9,314.38

874.15

0.60

1.00

0.63

0.32

0.60

0.66

0.67

–0.02

0.67

Width, mm [irina, mm

2,716.63

170.42

0.72

0.63

1.00

0.59

0.47

0.80

0.84

0.12

0.82

Height, mm Visina, mm

3,710.45

133.33

0.53

0.32

0.59

1.00

0.34

0.64

0.65

0.35

0.70

Clearance, mm Odignutost vozila od podloge, mm

637.36

57.64

0.53

0.60

0.47

0.34

1.00

0.58

0.60

–0.08

0.61

Mass, kg Masa, kg

15,183.75 3,038.63

0.82

0.66

0.80

0.64

0.58

1.00

0.85

0.11

0.84

Payload, kg Nosivost, kg

12,672.46 2,702.39

0.81

0.67

0.84

0.65

0.60

0.85

1.00

0.12

0.89

Crane reach, m Doseg dizalice, m Lifting moment (gross), kN Bruto podizni moment dizalice, kN

8.88

1.21

0.08

–0.02

0.12

0.35

–0.08

0.11

0.12

1.00

0.27

107.10

24.42

0.79

0.67

0.82

0.70

0.61

0.84

0.89

0.27

1.00

assortments were counted and the number of the identification plastic tag was recorded in case of large sawtimber and veneer assortments. In other cases (with small assortments – pulpwood and long firewood), direct measurement of processed assortments took place, whereby data on tree species, mean diameter and length were entered into a corresponding form. The ground bearing capacity was determined for each individual cycle, by visual estimate of the recorder. The soil bearing capacity was studied in line with the modified classification of ground bearing capacity that was already used in similar form within the research of machine performance in areas of the Croatian lowland forests (Por{insky 2000). Under this classification, forest soils were classified into the following load-bearing groups, and it was applied in further analyses: Þ Soil of good load-bearing capacity – firm and moderately firm soil. It includes dry, frozen or occasionally wet soil which presents no problems for moving vehicles. By a single pass of the vehicle, the tracks depth amounts to less than 5 cm,

and by multiple passes the depth amounts up to 25 cm, maximum 30 cm. When walking on such soil, shoe soles are dry or humid. Þ Soil of limited load-bearing capacity – soft and very soft soil. It is a soil that is partly to fully saturated with water. Walking on it is difficult, tracks of shoes are fully visible. Sinking of vehicles into the ground and slipping of wheels are appeared, vehicle speed is reduced, and after a single pass, the mineral layer of the soil can be exposed. Implementation of semi-tracks on the rear wheels of bogie axle and chains on the front wheels of single axle is recommended to obligatory (in extremely unfavorable conditions). Before starting the recording, an online form for the input of recorded data was developed. The form was developed using.NET technology and it could be found at the address http://norme.hrsume.hr. At the end of the work process recording, each recorder would register to the stated webpage and enter the data into the integral database. MSSQL database was used. Croat. j. for. eng. 33(2012)1

Productivity Models for Operational Planning of Timber Forwarding in Croatia (61–78)

4. Results of the research – Rezultati istra`ivanja 4.1 Forwarder classification – Razredba forvardera Forwarder analysis was carried out in the program package Statistica 08. In this analysis, the following vehicle morphological values were used: length, width, height to the cab roof, clearance of the vehicle from the ground, mass, payload, reach and lifting moment of the hydraulic crane. For the values whose data were not available in the established database, substitution was made with the value of the arithmetic mean of that variable. Database contains variables for 56 forwarders. Through a thorough consideration of the effect of available data on morphological characteristics of vehicles, the connection of the vehicle mass with most other values is evident (Table 2), which is logical due to the fact that the existence of mass determines the occurrence of other features. Vehicle mass is mostly correlated to the power of the engine and to payload and it is the key parameter, on which all other forwarder characteristics, except the hydraulic crane reach, are dependent. If the mass value increases, all other vehicle characteristics increase, too. Payload (PL, load capacity) is one of the most important exploitation characteristics of forwarders. By reviewing the vehicles’ technical characteristics database it can be determined that mass and load capacity of forwarders are approximately the same. The highest correlation to other values is indicated precisely by the PL of the vehicle (Table 2). For this reason, PL was used for the classification of forwarders. The k-mean algorithm was used for grouping of forwarders. This algorithm assigns each item to the group whose centroid is closest to it. Centroid is a point created by calculating the arithmetic mean for each dimension, separately for each item in the group. By implementing the mentioned algorithm, grouping of data into groups based on PL was made. The first group includes forwarders whose PL is closest to the centroid of 9,929 kg. The second group includes those whose PL is closest to the centroid value of 12,125 kg, while the third group is formed by forwarders whose PL is closest to the value of 15,571 kg. Distribution of variables, payload and other technical features according to forwarder class are shown in Fig. 3. Through further analysis for the needs of operative classification of forwarders, rough borderlines can be set among three forwarder classes by their PL, and those are: 11,000 kg and 14,000 kg. The first class Croat. j. for. eng. 33(2012)1

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consists of vehicles whose PL is less than 11,000 kg, the second of those whose PL amounts from 11,000 to 14,000 kg, while the third class consists of forwarders whose PL is above 14,000 kg. As it is obvious that the increase of PL in the forwarder family results in the increase of other studied dimensions, it can be concluded that there are three forwarder classes – light, medium and heavy forwarders. In line with the performed classification it can be determined that light forwarders are not used in the Croatian forestry. Therefore further research will be focused on the medium and heavy forwarders. Timberjack 1210 and Valmet 840 fall into the class of medium forwarders, whereas Timberjack 1410, Timberjack 1710 and Valmet 860 are in the class of heavy forwarders.

4.2 Characteristics of assortments and vehicle load – Zna~ajke sortimenata i tovara forvardera In order to gain insight into the load characteristics (mean volume and mean diameter), data from 1532 working sites were analysed, where timber extraction was carried out by forwarders over the last few years (since the beginning of full implementation of information production subsystem HsPPI and HsPro). Work sites were situated in the area of the Croatian lowland forests, and they are characterized by motor-manual felling and assortment method of timber processing along with the timber extraction by forwarders. Each point in Fig. 4 represents average value for individual felling site. Two groups of assortment size can be detected (Fig. 4). The first group is formed by the classes of large assortments of bigger dimensions – veneer logs, sawlogs (1st, 2nd and 3rd class) and logs for peeling. The second group includes small assortments, usually of smaller dimensions – long firewood, mining wood and thin industrial roundwood. Both assortment groups show a large dissipation of raw data, which is a consequence of buck-to-quality (BTQ) and assortment method of timber processing. Dependence of the number of loaded assortments on the decrease of soil bearing capacity has been determined (Fig. 5). By decrease of soil bearing capacity, the number of loaded roundwood assortments is reduced as well. In some cases, the overload of forwarder was noticed in conditions of limited soil bearing capacity, aimed at increasing productivity in spite of the decrease of vehicle speed. This can be explained by the subjective influence of some forwarder operators and their overloading of the vehicle in unfavourable conditions, all with the goal of increasing the work efficiency. Reduction of load-

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Fig. 3 Some technical features according to forwarder class Slika 3. Neke tehni~ke zna~ajke pojedinih razreda forvardera 68

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Fig. 4 Characteristics of roundwood from Croatian lowland forests Slika 4. Zna~ajke oblovine iz hrvatskih nizinskih {uma

Fig. 5 Number of roundwood pieces in the bunk area of forwarder Slika 5. Broj komada oblovine u tovarnom prostoru forvardera ed assortments in conditions of reduced soil bearing capacity was more expressed with the large than with the medium size forwarders. The analysis that was carried out, i.e. the modelling of the mean assortment volume, is the input Croat. j. for. eng. 33(2012)1

indicator for determining further load characteristics. One of the most important parameters is also the number of loaded assortments (Fig. 5). The product of mean assortment volume and number of assortments gives the load volume (Vl = Va Ă&#x2014; n).

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Productivity Models for Operational Planning of Timber Forwarding in Croatia (61–78)

4.3 Modeling of the forwarder productivity Oblikovanje proizvodnosti forvardera The forwarding productivity was studied using the time study on totally 1440 recorded work cycles, out of which 651 cycles were performed with medium, and 789 with heavy forwarders. 4.3.1 Time consumption of loaded and unloaded vehicle travel – Utro{ak vremena vo`nji optere}enoga i neoptere}enoga vozila Based on the dependence of time on the travel distance, the average speed of (un)loaded forwarders on forest road and off-road was calculated. The assumption was that forwarders move at uniform speed (Fig. 6). Medium size forwarders have a better mobility in the conditions of limited soil bearing capacity than heavy forwarders when they are unloaded. This is not the case in the conditions of good soil bearing capacity where heavy forwarders reach higher speeds. Larger differences in the vehicle speeds on the forest road between the forwarder classes are caused by bigger variety of conditions on the monitored sites in the areas of roadside landings. Based on the modeled driving speeds (arithmetic means of recorded speeds per turn, Fig. 6) of for-

warders and average traveling distances off-road (sof) and on the forest road (son), time consumption of a traveling is obtained. 4.3.2 Time consumption of timber loading Utro{ak vremena utovara drva Timber loading time covers the time of forwarder’s work in the felling area during loading, and the characteristic of this variable is that it does not change with the change of the forwarding distance. Forwarder’s work in the felling area starts with the end of the unloaded vehicle travel, or in other words, on the spot of the first loading. After loading the processed assortments within the reach of the hydraulic crane, the forwarder moves towards the next loading place, and continues doing so until reaching the optimal load. During timber loading (tl), two significantly different groups of work components can be detected (tl = tl1 + tl2): Þ Timber loading with crane (tl1) – the operator loads the timber into the bunk area using only the hydraulic crane, Þ Relocation of forwarder (tl2) – forwarder moves from one loading area to the other.

Fig. 6 Forwarders’ speed Slika 6. Brzine kretanja forvardera 70

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Fig. 7 Time consumption of timber loading Slika 7. Utro{ak vremena utovara drva Time consumption of timber loading by the hydraulic crane is dependent on the forwarder class and the number of loaded assortments. The recorded data are equalized by a linear model line from the source (Fig. 7, left). Timber loading expressed the influence of the »Volume-Piece Law«, as the smaller dimensions of the loaded roundwood, the number of loaded pieces and the crane time consumption have increased. Time consumption of forwarder relocation is impacted by the »Production Law«, i.e. by the quantity of the cut and processed timber per unit of area (Fig. 7, right). It is reflected in the exponential increase of time consumption of forwarder relocation due to diminished felling density (thinning) and vice versa (shelterwood and clear cutting). Relocation time consumption is higher within the group of heavy than medium forwarders. This is due to the fact that medium forwarders have larger hydraulic crane reach than heavy forwarders (Table 1). 4.3.3 Time consumption of timber unloading Utro{ak vremena istovara drva When the loaded forwarder ends its travel, its work starts on the roadside landing aimed at unloading, stacking and sorting of timber. Similar to the loading, the unloading at the roadside landing (tu) is additionally divided into two groups of work components (tu = tu1 + tu2): Þ Crane work time (tu1, where the operator works solely with the hydraulic crane with the goal of unloading the timber), and Croat. j. for. eng. 33(2012)1

Þ Relocation time during unloading (tu2, where the forwarder moves from pile to pile with the goal of separating timber by tree species and quality classes). Time consumption of crane unloading depends on the forwarder class and number of roundwood in the load. During unloading, the operators classify the timber according to tree species and quality classes, piling the unloaded timber onto separate stacks. The regression curve of recorded data is shown in Fig. 8. The asymptotic model was used. The increase of time consumption of crane unloading with reference to the increase of number of loaded assortments can be observed. It is decreased with the larger number of loaded assortments of smaller mean volume. This is explained by the fact that when unloading, the crane grips two or more pieces of roundwood assortments. The absence of wood classification and relocation has been noticed on a smaller part of observed research sites. This was conditioned by the stand characteristics (pure stands), silvicultural treatment (type of cutting), type of processing firewood, quality and dimensions of assortments and landing space. In the cases when timber was sorted on the roadside landing, higher time consumption of this work component was recorded. Mean time consumption for heavy forwarders was 0.84 min/turn, whereas for medium forwarders it amounted to 0.73 min/turn (Fig. 8, right). This phenomenon can be explained with the higher initial acceleration of medium forwarders.

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Fig. 8 Time consumption of timber unloading Slika 8. Utro{ak vremena istovara drva The sorting of assortments at the roadside landing has affected the decrease of forwarder efficiency in relation to its efficiency when not performing the timber separation when unloading. By the increase of forwarding distance, the negative effect of timber separation on forwarding efficiency is diminished, due to the growth of vehicle relocating share in the total cycle time. 4.3.4 Delays (downtime) and additional time factors – Prekidi rada i faktori dodatnoga vremena Delays consist of unavoidable and avoidable of work times. Various technological and organizational measures are taken to try and reduce it to the necessary level. The unavoidable delays are classified as preparatory time, occasional works and breaks. The avoidable delays include unnecessary conversations among workers, conversations between workers and passers-by and recorders, and excessive resting time. Vehicle breakdowns that cannot be eliminated without the intervention of a mechanic are also included into the avoidable delays. Avoidable and unavoidable delays per turn were taken into analysis together and they are shown in Fig. 9 (left). The additional time and additional time factor are determined through the analysis of unavoidable delays only. It was determined by this study that the additional time factors vary in a wide range and that they are higher than in previous studies. The average additional time was determined for each individual OS (Fig. 9, right). The value of the mean

additional time factor amounts to 1.33, or 33% of the effective time. Considering the structure of the additional time, it can be determined that the preparatory time accounts for 33%, occasional works for 33%, and personal breaks for 33% of the total unavoidable delays.

5. Implementation of the model into the information system – Ugra|ivanje modela u informacijski sustav One of the components of production planning process is the determination of norms for felling and processing, as well as for timber extraction. The existing norms (official and still in use) are inherited from times before the company H[ was founded (before 1990), and there are still a couple of regional systems functioning. In order to unify the norm system on the level of the company, »new norms« as a result of work of the Forestry Faculty Zagreb (project bearer) and H[ (project investor) were created. New norms have been integrated into the HsPPI program (Fig. 10). Determination of norms starts with the selection of the management unit (gospodarska jedinica) and type of yield (vrsta prihoda), followed with the list of the marked compartments/subcompartments from the Management Plan with all the data needed for norm calculation. Those are: type of yield (prihod), silvicultural form (uzgojni oblik) and total area of the compartment/subcompartment (povr{ina). For each compartCroat. j. for. eng. 33(2012)1

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Fig. 9 Share of delays in relation to effective time and additional time factor Slika 9. Udjeli prekida rada prema efektivnomu vremenu i faktor dodatnoga vremena

Fig. 10 Screenshot of tab for norm calculation for forwarders in HsPPI Slika 10. Prikaz zaslona ra~unala pri izra~unu normativa za forvardere u aplikaciji HsPPI ment/subcompartment from the list there is norm calculated for individual work phase, and this is made by selecting tabs: »Felling and Processing« (sje~a i izrada), »Extraction – Skidders« (privla~enje – Croat. j. for. eng. 33(2012)1

traktori) or »Extraction – Forwarders« (izvo`enje – forvarderi). The first step in the norm calculation process is the calculation of felling and processing norm, due

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to the fact that by selecting the work method, the final assortment structure is obtained, for whose extraction the norm is to be developed. From other data necessary for the development of forwarding norms, a part is taken from the Felling Plan (main tree species – glavna vrsta; volume of mean stand tree – SKS; net marked wood volume per unit of area – neto dozna~eno), while other parameters are entered (Fig. 10): machine type (tip stroja), equipped with semi-tracks (upotreba polugusjenica), soil-bearing capacity (nosivost tla), mean off-road forwarding distance (srednja udaljenost kretanja vozila po bespu}u), Þ mean forwarding distance on roadside landing (srednja udaljenost kretanja vozila po pomo}nom stovari{tu). Output data are norms for large (tehnika) and small assortments (TO i VM) per hour and per workday (8 hours) for selected work conditions. Through a thorough analysis carried out by forestry experts it was established that the productivity model presented in this study plans higher norms and decreased delay times than the existing ones (Tomi} 2007). Þ Þ Þ Þ

6. Conclusions – Zaklju~ci This research covered the analysis of the factors impacting forwarding, as a special aspect of primary transport of timber in the lowland forests of the Republic of Croatia. It is characteristic of timber harvesting systems in the area that felling is performed motor-manually and timber is processed by power chainsaws, timber is bucked according to its quality, and extraction of timber to roadside landings is fully mechanized. The method used is not the traditional cut-to-length (CTL), but buck-to-quality (BTQ) method. Aiming to develop an operationally implementable system of timber forwarding planning, forwarders were classified according to their technical characteristics. The most important factor appeared to be the payload, so this variable was used for clustering the vehicle types. Three classes of forwarders were determined: light, medium and heavy forwarders. Light forwarders have a load capacity of up to 11,000 kg, medium from 11,000 kg to 14,000 kg, and heavy forwarders above 14,000 kg. Light forwarders are not used in the Croatian forestry, and farm tractors with semi-trailers equipped with winch and hydraulic crane are used instead. Loaded roundwood features were determined with the goal of calculating productivity (norm projection) by modeling the volume of large and small

assortments from an average marked tree volume for all species represented in the lowland forests. The data were gathered by joining together two information subsystems HsPro and HsPPI. By the increase of marked tree volume, the average volume of large assortments grows exponentially, whereas with small assortments, after the initial growth, the relations take values closer to the asymptote of the curve (0.34 m3/pcs). The results of the forwarding productivity study are under a strong influence of the interaction of important factors prevailing in the Croatian lowland forests, and the study came to the following conclusions: Þ The forwarder class influences the level of forwarder productivity, and it does so primarily through its payload, or load volume, but also through its speed and time consumption during loading and unloading. Þ Diminished levels of timber extraction by forwarders are influenced by conditions of off-road soil-bearing capacities as a result of the increase of time consumption of forwarding, i.e. lower speed and lower load volume. Þ The use of semi-tracks, which provide the mobility of forwarders in unfavorable conditions, additionally lower the speed, increasing the time consumption of forwarding. Þ The increase of forwarding distances diminishes forwarder’s productivity, as the share of the time spent moving grows within the structure of the total time consumption of the work shift. However, the influence of distance on the forwarding productivity should be viewed through its interaction with the classes of soil-bearing capacity and classes of forwarders. Likewise, with the increase of forwarding distance, the load volume becomes more significant. Þ Stand conditions and forest management guidelines demonstrated the impact on the productivity of timber forwarding through the well known Laws of Mechanizing Forest Works, i.e. through felling density (Productivity Law), features and dimensions of processed roundwood (Volume-Piece Law and Product Type Law). Based on the obtained research results and requests of the company H[, a model of forwarder productivity for lowland forests was established and finally incorporated into the production information subsystem. Real data from the first planning stage (forest inventory data, tree marking plan, assortment structure plan, etc.) and developed forwarder productivity model, together with input work parameters ensures the objectivity of norms used in timber forwarding. Croat. j. for. eng. 33(2012)1

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Acknowledgements – Zahvala The research was conducted with the support of the company »Hrvatske {ume« d.o.o. that provided the financial support and insured the material and human resources for the execution of the project »Systematization of Norms for the Production of Timber Assortments – Norms for Forwarding«. The project bearer was the Faculty of Forestry of the University of Zagreb.

7. References – Literatura Anon., 2006: [umskogospodarska osnova podru~ja RH 2006.–2015. (Forest Management Plan, 2006–2015) Hrvatske {ume d.o.o., Zagreb. Anon., 2011: Godi{nje poslovno izvje{}e (Annual account). Hrvatske {ume d.o.o., Zagreb. Beuk, D., Toma{i}, @., Horvat, D., 2007: Status and development of forest harvesting mechanisation in Croatian state forestry. Croatian journal of forest engineering 28(1): 63–82. Bojanin, S., Krpan, A. P. B., 1994: Eksploatacija {uma pri razli~itim radnim uvjetima u Hrvatskoj. [umarski list 118 (9/10): 271–282. Bojanin, S., Krpan, A. P. B., 1997: Mogu}nost tzv. visokoga i potpunog mehaniziranja sje~e i izrade te mehaniziranja privla~enja drva u {umama Hrvatske (Possibilities for high level and complete mechanization in felling operations and mechanization in skidding in Croatian forests). [umarski list 121(7–8): 371–381. Brunberg, T., 1999: Battre lastutnyttjande hos skotare (Optimizing forwarder payloads). Skogforsk, Resultat 1:1–4. Brunberg, T., 2001: Hydroflex – nytt koncept för att utnyttja skotarnas lastkapacitet bättre (Hydroflex: a new system for maximizing forwarder payloads). Skogforsk, Resultat 13: 1–4. Brunberg, T., 2004: Underlag till produktionsnormer för skotare (Productivity-norm data for forwarders). Skogforsk, Redogörelse 3: 1–12. Flisberg, P., Forsberg, M., Rönnqvist, M., 2007: Optimization based planning tools for routing of forwarders at harvest areas. Canadian journal of forest research 37(11): 2153–2163. Freitag, B., Warkotsch, W., 2011: The use of swap bodies for skidding and roundwood transportation. In: Ackerman, P., Ham, H., Gleasure, E. (eds.), Fourth Forest Engineering Conference: Innovation in Forest Engineering – adapting to structural change, April 5–7, 2011 in White River, South Africa. Department of Forest and Wood Science (Stellenbosch University) in conjunction with IUFRO and FESA (Forest Engineering Southern Africa), pp. 130–130. Ghaffarian, M. R., Stampfer, K., Sessions, J., 2006: Forwarding productivity in Southern Austria. Croatian journal of forest engineering 28(2): 169–175. Croat. j. for. eng. 33(2012)1

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Horvat, D., [u{njar, M., 2001: Neke zna~ajke poljoprivrednih traktora prilago|enih {umskim radovima (Some characteristics of farming tractors used in forest work). In: Mati}, S., Krpan, A. P. B., Gra~an, J. (eds), Znanost u potrajnom gospodarenju hrvatskim {umama, Forestry Facultry Zagreb and Forestry Institute Jastrebarsko, Zagreb, Croatia, pp. 535–544. Horvat, D., Ze~i}, @., [u{njar, M., 2007: Morfolo{ke i proizvodne zna~ajke traktora Ecotrac 120V (Morphological characteristics and productivity of skidder ECOTRAC 120 V). Nova mehanizacija {umarstva 28 (Special Issue 1): 81–92. ISO, 2009: Machinery for forestry – Mobile and self-propelled machinery – Terms, definitions and classification (ISO 6814:2009). Machinery. 1–7. Jirou{ek, R., Klva~, R., Skoupý, A., 2007: Productivity and costs of the mechanised cut-to-length wood harvesting system in clear–felling operations. Journal of forest science 53(10): 476–482. Krpan, A. P. B., 1996: Problem privla~enja drva u nizinskim {umama Hrvatske (Problem of skidding timber in Croatian lowland forests). [umarski list 120(3/4): 151–156. Kühmaier, M., Stampfer, K., 2010: Development of a Multi-Attribute Spatial Decision Support System in Selecting Timber Harvesting Systems. Croatian journal of forest engineering 31(2): 75–88. Kuitto, P. J., Keskinen, S., Lindroos, J., Oijala, T., Rajamäki, J., Räsänen, T., Terävä, J., 1994: Puutavaran koneellinen hakkuu ja metsäkuljetus (Mechanized cutting and forest haulage, In Finnish, English summary). Metsäteho Report 410, pp. 1–38. Li, Y., Wang, J., Miller, G., McNeel, J., 2006: Production economics of harvesting small-diameter hardwood stands in central Appalachia. Forest products journal 56(3): 81–86. Lindroos, O., Wasterlund, I., 2011: Larger loads and decreased damage – the potential of a new forwarding concept. In: Ackerman, P., Ham, H., Gleasure, E. (eds.), Fourth Forest Engineering Conference: Innovation in Forest Engineering – adapting to structural change, April 5–7, 2011 in White River, South Africa. Department of Forest and Wood Science (Stellenbosch University) in conjunction with IUFRO and FESA (Forest Engineering Southern Africa), pp. 166–166. Löffler, H., 1989: Forstliche Verfahrenstechnik für Studierende der Forstwissenschaft (Manuscript). Universität München, pp. 1–516. Lugmayr, J., Bauer, R., Gatterbauer, E., Hauer, H., Kindermann, G., Preier, P., Schnabel, G., Schönauer, H., 2009: »Forstmaschinen-CD, 4. Auflage«. Bundesforschungs und Ausbildungszentrum für Wald Naturgefahren und Landschaft (BFW), Institut für Waldwachstum und Betriebswirtschaft, Wien, Austria, CD-ROM. Mederski, P. S., 2006: A comparison of harvesting productivity and costs in thinning operations with and without midfield. Forest ecology and management 224(3): 286–296.

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Miheli~, M., Kr~, J., 2008: Analysis of Inclusion of Wood Forwarding into a Skidding Model. Croatian journal of forest engineering 30(2): 113–125.

Samset, I., 1990: Some observations on time and performance studies in forestry. Meddelelser fra Norsk Institutt for Skogforskning. 43(5): 1–80.

Minette, L. J., Moreira, F. M. T., de Souza, A. P., Machado, C. C., Silva, K. R., 2004: Análise técnica e econômica do forwarder em três subsistemas de colheita de florestas de eucalipto (Technical and economic analysis of a forwarder under three eucalyptus forest harvest subsystems). Revista Árvore 28(1): 91–97.

Samset, I., 1992: Forest operations as a scientific discipline. Meddelelser fra Skogforsk. 44(12): 1–48.

Nurminen, T., Korpunen, H., Uusitalo, J., 2006: Time consumption analysis of the mechanized cut–to–length harvesting system. Silva Fennica. 40(2): 335–363.

Sever, S., 1988: Proizvodnost i perfomanse forvardera u radovima privla~enja drva. Mehanizacija {umarstva 18(5–6): 59–87.

Pandur, Z., Vusi}, D., Papa, I., 2009: Dodatna oprema za pove}anje proizvodnosti forvardera. Nova mehanizacija {umarstva 30: 19–25.

Slabak, M., 1983: Forvarderi u svijetu i kod nas. Mehanizacija {umarstva u teoriji i praksi. Opatija, pp. 351–362.

Pentek, T., Pi~man, D., Neve~erel, H., Lepoglavec, K., Papa, I., Poto~nik, I., 2011: Primarno otvaranje {uma razli~itih reljefnih podru~ja Republike Hrvatske (Primary Forest Opening of Different Relief Areas in the Republic of Croatia). Croatian journal of forest engineering 32(1): 401–416. Pentek, T., Por{insky, T., [u{njar, M., Stanki}, I., Neve~erel, H., [por~i}, M., 2008: Environmentally Sound Harvesting Technologies in Commercial Forests in the Area of Northern Velebit – Functional Terrain Classification. Periodicum biologorum 110(2): 127–135. Por{insky, T., 1997: Odre|ivanje poloàja Kockumsa 850 i Timberjacka 1210 u obiteliji forvardera morfolo{kom ra{~lambom (The morphological analysis determination of the Kockums 850 and Timberjack 1210 positions in the forwarder family). Mehanizacija {umarstva 22(3): 129–138. Por{insky, T., 2000: îmbenici u~inkovitosti forvardera Timberjack 1210 pri izvoènju oblog drva glavnog prihoda nizinskih {uma Hrvatske (Efficiency factors of Timberjack 1210 at forwarding the main felling roundwood in Croatian lowland forests). Forestry Faculty, University of Zagreb, MSc Thesis, pp. 1–140. Por{insky, T., 2002: Productivity factors of Timberjack 1210 at forwarding the main felling roundwood in Croatian lowland forests. Glasnik za {umske pokuse 39: 103–132. Por{insky, T., 2005: Djelotvornost i ekolo{ka pogodnost forvardera Timberjack 1710 pri izvoènju oblovine iz nizinskih {uma Hrvatske (Efficiency and environmental evaluation of Timberjack 1710B forwarder on roundwood extraction from Croatian lowland forests). PhD Thesis, Forestry Faculty, University of Zagreb, pp. 1–170. Por{insky, T., Stanki}, I., Bosner, A., Pentek, T., 2008: Morphological analysis of chainsaws. In: III International scientific conference FORTEHENVI, 26–30 May 2008. Prague, Czech Republic, POSTER. Raymond, K. A., 1989: Mechanised shortwood thinning with forwarder extraction (Project Report 42). New Zealand Logging Industry Research Association, pp. 1–17. Sabo, A., Por{insky, T., 2005: Skidding of fir roundwood by Timberjack 240C from selective forests of Gorski Kotar. Croatian journal of forest engineering 26(1): 13–27.

Sever, S., 1980: Istra`ivanje nekih eksploatacijskih parametara traktora kad privla~enja drva. Forestry Faculty, University of Zagreb, PhD Thesis, pp. 1–301.

Stanki}, I., 2010: Vi{ekriterijsko planiranje izvo`enja drva forvarderima iz nizinskih {uma Hrvatske (Multicriterial planning of timber forwarding in Croatian lowland forests). Forestry Faculty, University of Zagreb, PhD Thesis, pp. 1–123. Suvinen, A., 2006: Economic comparison of the use of tyres, wheel chains and bogie tracks for timber extraction. Croatian journal of forest engineering 27(2): 81–102. [u{njar, M., 1998: Istra`ivanje ovisnosti nekih tehni~kih zna~ajki ivera~a morfolo{kom ra{~lambom (Research of some chipper´s technical features by morphological analysis). Mehanizacija {umarstva 23(3–4): 139–150. [u{njar, M., Bori}, D., 2008: Morfolo{ka ra{~lamba farmerskih vitala (Morphological analysis of farmi winches). Nova mehanizacija {umarstva 29: 29–35. [u{njar, M., Horvat, D., Grahovac, I., 2007: Morfolo{ka ra{~lamba {umskih hidrauli~nih dizalica (Morphological analysis of forest hidraulic cranes). Nova mehanizacija {umarstva 28: 15–26. Tiernan, D., Zeleke, G., Owende, P. M. O., Kanali, C. L., Lyons, J., Ward, S. M., 2004: Effect of working conditions on forwarder productivity in cut-to-length timber harvesting on sensitive forest sites in Ireland. Biosystems engineering 87(2): 167–177. Tomi}, I., 2007: Kako racionalizirati kori{tenje mehanizacije. Hrvatske {ume, no. 123: 11–12. Tufts, R. A., 1997: Productivity and cost of the Ponsse 15–series, cut–to–length harvesting system in southern pine plantations. Forest products journal 47(10): 39–46. Tufts, R. A; Brinker, R. W., 1993: Productivity of a Scandinavian system while second thinning pine plantations. Forest products journal 43(11/12): 24–32. Väätäinen, K., Asikainen, A., Sikanen, L., 2006: The cost effect of forest machine relocations on logging costs in Finland. Forestry Studies, Metsanduslikud Uurimused 45, pp. 135–141. Väkevä, J., Kariniemi, A., Lindroos, O., Poikela, A., Rajamäki, J., Uusi-Pantti, K., 2001: Puutavaran metsäkuljetuksen ajanmenekki (Time consumption of timber haulage). Metsätehon raportti 123, pp. 1–41. Croat. j. for. eng. 33(2012)1

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Sa`etak

Modeli proizvodnosti pri operativnom planiranju izvoènja drva forvarderima u Hrvatskoj U podru~ju hrvatskih nizinskih {uma za skupljanje i privla~enje drvnih sortimenata primjenjuje se poseban oblik primarnoga transporta drva, za koji je znakovita potpuna odignutost tereta (oblovine) od tla, pri ~emu se koriste forvarderi. Forvarderi su samopogonjena vozila namijenjena pomicanju stabala ili njegovih dijelova koji drvo izvoze utovareno u tovarnom prostoru vozila iz {umskoga bespu}a do pomo}noga stovari{ta, odnosno {umske ceste. U sklopu istraìva~koga projekta »Usustavljenje normi i normativa«, koji financiraju Hrvatske {ume d.o.o., razvijene su nove proizvodne norme izvoènja drva forvarderima. Proizvodnost izvoènja drva ovisi o kori{tenom tipu vozila. Stoga je za provedbu istraìvanja bilo potrebno prikupiti podatke o tehni~kim zna~ajkama novijih forvardera u Republici Hrvatskoj, ali i u svijetu. Potom se pristupilo morfolo{koj ra{~lambi na osnovi koje su se vozila razvrstala u razrede, jer je neodrìvo projektirati normu za svaki tip vozila zasebno. Klasterskom analizom dobivena su tri razreda forvardera. To su laki, srednje te{ki i te{ki forvarderi. Kao najva`niji ~imbenik pri razvrstavanju pokazala se nosivost forvardera. Laki su nosivosti do 11 t, srednje te{ki od 11 do 14, a te{ki forvarderi imaju nosivost ve}u od 14 t. U hrvatskom {umarstvu koriste se uglavnom srednje te{ki i te{ki forvarderi, dok se umjesto lakih forvardera koriste razne ina~ice traktorskih ekipaà. Primjena izvoènja drva razumijeva sortimentnu metodu izradbe oblovine. Stoga su zna~ajke tovara (prosje~an obujam komada i njegove dimenzije) posredno uvjetovane i prosje~nim dimenzijama dozna~enih stabala za sje~u i izradbu. Spojeni su podaci iz dviju aplikacija (HsPPI i HsPRO) za ona radili{ta na kojima se od po~etka primjene tih aplikacija izvozilo forvarderima. Na osnovi podataka o doznaci stabala oblikovane su zna~ajke oblovine u etatu najzastupljenijih vrsta drva. Informati~ka slu`ba poduze}a Hrvatske {ume d.o.o. preuzela je zadatak izrade sustava za prikupljanje i pohranu snimljenih podataka. Za pohranu se koristila baza podataka MS SQL Server 2000. Kao korisni~ko su~elje za prihvat podataka sluìla je web-aplikacija zasnovana na dinami~nim mre`nim stranicama koje se u potpunosti izvr{avaju na posluìteljskom ra~unalu i izravno komuniciraju s bazom podataka. Sustav je izra|en pomo}u tehnologije Microsoft ASP.NET, programiran u Visual Basic.NET-u, a izvr{ava se na posluìtelju Windows Server 2003. Rad je forvardera istraèn na 22 radili{ta metodama studija rada i vremena, primjenom povratne metode kronometrije. Radi {to korektnijega oblikovanja utro{aka vremena tim su podacima pridruèni i podaci prethodnih istraìvanja, opsega 8 radili{ta, te je oblikovanje utro{aka vremena rada zasnovano na podacima s ukupno 30 radili{ta. Pri ra{~lambi su upotrijebljeni prikupljeni podaci o sastojinskim i terenskim utjecajnim ~imbenicima izvoènja drva. Pri planiranju privla~enja drva, kao najzahtjevnijoj sastavnici pridobivanja drva, postavljaju se zahtjevi za poznavanjem prisutnih utjecajnih ~imbenika odre|enoga podru~ja te njihova djelovanja na djelotvornost kori{tenih sredstava privla~enja drva. Va`niji utjecajni ~imbenici izvoènja drva iz sje~ina hrvatskih nizinskih {uma nastali iz ovoga istraìvanja svakako su srednja udaljenost privla~enja, nosivost podloge (tla), obujam prosje~noga komada oblovine u tovaru, sje~na gusto}a te nosivost forvardera. Regresijskom ra{~lambom utvr|ena je ovisnost trajanja pojedinih sastavnica rada o utjecajnim ~imbenicima te je izra|en model proizvodnosti forvardera. Po zavr{etku istraìvanja dobiveni je model prema zahtjevima naru~itelja ugra|en u program HsPPi. Tu je aplikaciju razvila Informati~ka slu`ba poduze}a Hrvatske {ume d.o.o., a koristi se za planiranje proizvodnje. Glavni su dijelovi sustava za pripremu proizvodnje: priprema doznake, plan sje~a, plan proizvodnje i plan prodaje.

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Unutar dijela za izradu plana proizvodnje nalazi se i modul za izra~un normativa izvoènja drva forvarderima. Ovdje razvijen i opisan sustav za planiranje normativa izvoènja drva forvarderima uskoro zapo~inje s operativnom primjenom u hrvatskom dràvnom {umarstvu. Klju~ne rije~i: forvarder, norme proizvodnosti, planiranje, nizinske {ume, Hrvatska

Authors’ addresses – Adresa autorâ: Igor Stanki}, PhD e-mail: igor.stankic@sumfak.hr Assoc. Prof. Tomislav Por{insky, PhD e-mail: porsinsky@sumfak.hr Department of forest engineering Forestry Faculty, University of Zagreb Sveto{imunska 25, HR-10000 Zagreb CROATIA

Received (Primljeno): September 25, 2011 Accepted (Prihva}eno): May 22, 2012

@eljko Toma{i}, PhD e-mail: zeljko.tomasic@hrsume.hr Ivica Tonkovi}, dipl. ing. e-mail: ivica.tonkovic@hrsume.hr Marko Frnti}, dipl. ing. e-mail: marko.frntic@hrsume.hr Hrvatske {ume d.o.o. (Croatian forests LLC) Directorate Vukotinovi}eva 2, HR-10000 Zagreb CROATIA Croat. j. for. eng. 33(2012)1

Original scientific paper – Izvorni znanstveni rad

Energy Use of and Emissions from the Operation Phase of a Medium Distance Cableway System Radomír Klva~, Radek Fischer, Alois Skoupý Abstract – Nacrtak This paper presents an assessment of the life cycle operation phase of forest cableways Larix 550 and Larix 3T with respect to energy requirements and environmental pollution caused by emissions. Energy audit quantifies energy use based on the consumption of fuels and lubricants. Energy balance includes both the energy content and the energy needed for the production of fuels and lubricants. Fuel consumption measured for one year ranged from 1.2 – 1.4 l/m3. Based on the consumption of fuels and lubricants the paper quantifies the amount of emissions in two scenarios (minimum consumption and maximum consumption) with a special focus on GHG emissions. Calculations are made of emissions for diesel fuel and for the alternatively applicable rape-seed methyl ester (RME), and a calculation is also made of emissions originating from fossil sources. By using RME as a fuel, the amount of CO2 emissions from fossil sources discharged into the environment can be reduced by 3.4 kg per a cubic meter over the bark of timber extracted by cableway. Keywords: GHG emissions, energy audit, fuel consumption, oil consumption

1. Introduction – Uvod Anthropogenic greenhouse gases essentially affect the climate and a reduction of their emission into environment is one of primary objectives of the current EU environmental policy. In order to achieve the goal, it is absolutely necessary to increase the share of energy from renewable sources, where in fact a zero balance of CO2 originating from fossil resources can be expected. However, clear zero balance of carbon dioxide is impossible in this case because of fossil fuel consumption during production of renewable energy sources. Nowadays each product is loaded with a certain share of primary fossil resources and hence with a share of Green House Gas (GHG) emissions into environment. The impact of any technology (system) or product onto environment can be assessed by LCA methodology, which can identify inputs and outputs including their environmental impact (ISO 14040-2 standards, revised in 14044). Also the main source of energy for logging and hauling machines used in forest operations are fossil fuels. Klvac et al. (2003) quantified the share of indiCroat. j. for. eng. 33(2012)1

vidual phases of the machine life cycle in the total energy consumption of fully mechanized technology in the conditions of Ireland. Phases included in the calculations were as follows: machine manufacture, repairs (including maintenance) and operation. The phase of disposal or recycling, which also participates in the energy balance, was not included. Results of research showed that the share of machine operation phase in the total energy balance amounts to approximately 80%. Athanassiadis (2000) established the energy use and the amount of emissions from a fully mechanized technology in Sweden at 82 MJ per cubic meter of wood processed, presenting the values of emissions for three fuel types: EC3, EC1 and RME. However, in his work the emissions are only quantified without establishing their share of fossil resources. Berg (1996 and 1997) compared emissions from motor-manual and mechanized technologies in clear felling and shelterwood felling on the basis of the amount of combusted fuel. His works demonstrate that mechanized technology loads environment with emission substances rather more than motor-manual technology, and that shelterwood system puts

Radomír Klva~ et al.

Energy Use of and Emissions from the Operation Phase of a Medium Distance System (79–88)

on environment a greater load of CO2 and NOx emissions than clear-felling system due to a higher number of machine passes and their lower productivity. Karjalainen and Asikainen (1996) and Sambo (1997) estimated fuel consumption in the forestry of Finland and Canada. Based on the estimates, Karjalainen and Asikainen (1996) established the amount of emissions into environment. The expected CO2 emissions can be determined on the basis of molecular formula, carbon-hydrogen ratio (C:H), energy content and other factors (Calais and Sims 2006). However, as they mentioned, the simple calculation of CO2 emissions based on the C:H ratio on stoichiometric basis is rather naive because the emissions and their composition are also affected by other factors. Moreover, the energy content in fuels was published by many authors with different results. Grägg (1994, 1998, 1999) and Furuholt (1995) established fuel energy content as follows: EC3 (Swedish Environmental Class 3 Fuel) = 36 MJ/l, EC1 (Swedish Environmental Class 1 Fuel) = 35.3 MJ/l, and RME (Rapeseed Methyl Ester) = 33.1 MJ/l. Altin et al. (2001) determined the energy

Table 1 Emission factors of diesel engine (g/MJ of engine output) generated in combustion (Athanassiadis 2000) Tablica 1. Faktori emisije dizelskih motora pri sagorijevanju, g/MJ (Athanassiadis 2000) CO2

NOX

Diesel

260

1.26

0.114

2.342

0.197

RME

260

0.87

0.022

2.917

0.148

content of diesel fuel at 36.14 MJ/l, McDonell (1996) mentions the value of 36.55 MJ/l for diesel and 35.67 MJ/l for a mixture with 25% of semi-refined rapeseed oil and 75% of diesel. Emissions generated in combustion can be related to the engine output power, where they depend on thermal efficiency, i.e. on the capacity of transforming fuel energy to engine efficiency. Thermal efficiency of engines depends on the rate of compression and on the octane or cetane number of the fuel. Hamilton (2000) presented the relation between thermal efficiency, compression ratio and octane number for carbureted spark-ignition engines.

Table 2 Emission factors of compression–ignition engines (C) and spark–ignition engines (S) in various machines as related to engine output power (kg/kWh) (USEPA 1985) Tablica 2. Faktori emisije dizelskih (C) i benzinskih (S) motora kod razli~itih strojeva s obzirom na snagu motora (kg/kWh) (USEPA 1985) Wheeled tractor Kota~ni traktor

Scraper Skrejper

Wheeled dozer Kota~ni dozer

1.90E-01

4.70E-03

3.28E-03

2.06E-03

3.78E-04

3.41E-04

2.15E-04

3.75E-04

1.62E-04

1.05E-02

1.60E-02

8.54E-03

1.09E-02

1.00E-02

9.57E-03

PM10

9.28E-04

1.70E-03

4.84E-04

5.51E-04

1.06E-03

8.38E-04

SO2

1.14E-03

3.04E-04

1.16E-03

1.21E-03

1.17E-03

VOCs

1.01E-03

2.36E-03

7.16E-03

5.00E-04

7.40E-04

4.80E-04

Off-highway truck Terenski kamion

Pollutant Zaga|iva~

Track-type tractor Vrsta stroja

2.88E-03

9.84E-03

Formaldehyde

2.28E-04

NOX

Tracked loader Utovariva~ gusjeni~ar

3.63E-03

2.19E-01

3.03E-03

4.70E-03

8.08E-03

2.71E-01

6.16E-03

2.66E-01

Formaldehyde

2.64E-04

2.98E-04

1.34E-04

2.95E-04

2.63E-04

3.43E-04

2.72E-04

2.98E-04

NOX

1.18E-02

7.27E-03

1.25E-02

1.09E-02

1.75E-02

7.08E-03

1.48E-02

6.48E-03

PM10

1.08E-03

4.21E-04

8.78E-04

6.73E-04

1.04E-03

5.27E-04

1.21E-03

4.06E-04

SO2

1.15E-03

3.19E-04

1.14E-03

1.19E-03

1.34E-03

3.73E-04

1.25E-03

3.54E-04

VOCs

1.59E-03

7.46E-03

1.49E-03

5.00E-04

1.30E-03

1.24E-02

1.35E-03

8.70E-03

Pollutant Zaga|iva~

Wheeled loader Kota~ni utovariva~

Grader Grejder

Roller Valjci

Miscellaneous Razni strojevi

Conversion from kWh to MJ: 1 kWh = 3.6 MJ – Pretvorba iz kWh u MJ: 1 kWh = 3,6 MJ PM10 – particular matters up to 10 microns and less – Sitne ~estice <10 mikrona VOCs – volatile organic compounds – [tetni organski spojevi

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Energy Use of and Emissions from the Operation Phase of a Medium Distance System (79–88)

Radomír Klva~ et al.

Table 3 Total emissions generated in petroleum (P) and diesel (D) manufacture by individual countries (Davison and Lewis 1999) Tablica 3. Ukupna emisija iz proizvodnje benzinskih i dizelskih goriva, po dr`avama (Davison i Lewis 1999) Country Dr`ava Austria / Austrija Belgium / Belgija Denmark / Danska Finland / Finska France / Francuska Germany / Njema~ka Greece / Gr~ka Ireland / Irska Italy / Italija Netherlands / Nizozemska Portugal / Portugal Spain / [panjolska Sweden / [vedska Switzerland / [vicarska UK / Engleska

CO2 (kg/GJ) P 9.4 9.2 9.0 9.3 9.3 9.2 9.5 8.9 9.3 9.2 9.3 9.3 9.2 9.0 9.3

D 6.8 6.8 7.2 7.0 6.7 6.9 7.2 7.2 7.0 6.8 6.9 6.9 7.0 7.2 6.8

CO (g/GJ) P 5.4 5.1 5.1 5.6 5.1 5.1 5.8 5.0 5.4 5.1 5.4 5.4 5.5 5.4 5.1

D 5.0 4.6 4.6 5.1 4.6 4.6 5.3 4.5 4.9 4.6 4.9 4.9 5.0 4.8 4.6

NOX (g/GJ) P 45.7 42.2 43.2 45.6 42.2 43.2 49.3 42.5 46.0 42.4 45.2 45.2 44.7 45.8 42.4

D 39.1 36.0 38.0 39.4 35.8 37.1 43.2 37.4 39.9 36.2 39.0 39.0 38.8 40.5 36.1

VOCS (g/GJ) P 213.0 211.5 203.5 208.7 212.3 208.3 208.9 203.5 208.8 209.8 210.2 210.0 208.0 203.5 211.4

D 87.9 87.6 86.1 87.4 87.8 87.3 87.2 86.2 87.3 87.6 87.4 87.5 87.0 86.1 87.8

SO2 (g/GJ) P 62.7 65.6 93.3 77.7 62.7 78.1 79.5 93.1 77.9 72.2 72.2 73.3 78.4 95.1 66.9

D 45.1 48.4 77.7 57.5 44.9 57.8 62.7 77.5 59.0 51.8 55.2 54.5 61.8 79.4 47.6

CH4 (g/GJ) P 17.4 17.4 17.2 17.3 17.3 17.3 17.3 17.0 17.2 17.4 17.3 17.3 17.1 16.9 17.4

D 15.7 15.7 15.6 15.6 15.7 15.7 15.7 15.5 15.6 15.7 15.7 15.7 15.5 15.3 15.8

PM (g/GJ) P 2.7 2.4 1.8 2.4 2.5 2.2 2.4 1.8 2.3 2.3 2.4 2.4 2.3 1.9 2.4

D 1.1 1.0 1.4 1.3 1.0 1.2 1.4 1.4 1.2 1.1 1.2 1.2 1.3 1.4 1.1

PM – particular matters – Sitne ~estice VOCs – volatile organic compounds – [tetni organski spojevi

Emission factors of compression-ignition engines in combustion for harvester technologies were studied by Grägg (1999). They were established on engine Perkins 1006-T (133.5 kW) for EC3 fuel and on engine Valmet 420 DS (135.8 kW for EC3 and EC1 fuels). RME emission factors were established by Grägg (1994) on engine Scania DSC 1127 (144 kW). Based on the measurements, Athanassiadis (2000) determined emission factors of compression-ignition engines per engine output in MJ – these are presented in Table 1. In this study engine thermal efficiency was set up for both fuels at a level of 40%. Emission factors need to be expressed at the best for each machine separately or the machines should be at least put together to form appropriate groups. Emission factors of various machine groups are studied and regularly updated by the United States Environmental Protection Agency (USEPA 1985). Table 2 presents emission factors for various machine groups with both spark- and compression-ignition engines. Emissions generated by combustion however do not include all noxious substances emitted into the environment from the use of fuels. A general comparison must take into account leakages of operation fluids and the share of emissions generated in the extraction, production, transport and distribution of Croat. j. for. eng. 33(2012)1

fuels. Emissions developing during the production of fuels were studied by Davison and Lewis (1999) and Table 3 presents these emissions in some selected countries. The study was focused on the most energy demanding part of the machine life cycle i.e. production phase. The objective was to quantify the amount of energy required for an extraction of functional unit of production (m3) by cableways and to establish the amount of emission load on environment.

2. Material and Methods – Materijal i metode Cableway types assessed within the study were Model Larix 550 and Model Larix 3T. The powering and transport unit was a farm tractor. The cableway Model Larix 550 is designed as a complete superstructure on the farm tractor (ZETOR 8540, 9540, 10540, or comparable types NEW HOLLAND, SAME, STEYR, JOHN DEERE), which provides a considerable advantage for passability through the terrain and alleviates laboriousness of cableway construction in the field. The cableway can be used universally with a possibility of timber skidding down the hill (100 – 550 m), up the hill and on the

Radomír Klva~ et al.

Energy Use of and Emissions from the Operation Phase of a Medium Distance System (79–88)

plain, with a fully suspended or semi-suspended load. Based on the terrain character the assembly can be made with a running line or with a skidding line. Basic technical parameters: pulling force 35 kN, reach 550 m, carrying capacity 2 tons, time consumption for track construction 48 hrs. The cableway Model Larix 3T is a follow-up to Model LARIX 550 from which the concept was adopted with the running line, capstan and suspension onto the rear and front three-point linkage of a tractor. It differs in a reinforced load-bearing structure, simplified design and operation, greater capacity of drums and line boards. Carrying capacity of the Model LARIX 3T is increased to 3 tons and reach up to 850 m. The system boundaries were set for the extraction chain from stump to road side (felling, delimbing and cross-cutting was not taken into the account) in operation phase of cableway life cycle. The Functional Unit (FU) used in the analyses was cubic meter of wood over bark (m3). In cases when the calculated values were too small the unit 1000 m3 was used. The model that was calculated in this study had the following data inputs: Þ Fuel, engine oil and transmission oil consumption, liters, Þ Grease consumption, kg, Þ Type of fuel: mineral or rape methyl esterm, RME, Þ Type of oil in respect to biodegradability: mineral, synthetic or vegetable. Note: Biodegradability is defined by CEC-L-33A-93, which is an international assignation of fuel and grease production. A product is regarded as biodegradable if it is degraded by at least 80% in 21 days (CEC 1995). Raw vegetable oils have a biodegradability of around 98% (if there are additives included, it is 90–98%). Mineral oils have a biodegradability of about 20% and biodegradability of synthetic oils varies from 20 to 92% depending on the type (Anon. 1994). An energy audit should include the combustion energy value of fuels and oils, and the energy used during their production. Athanassiadis (2000) estimated a combined fuel and oil energy use for harvesting and forwarding of 82 MJ per m3ub (cubic meter under bark), however the calculation failed to include the energy used during the production of oils. The energy consumed during the production of diesel fuel is reported as ca. 4.5 MJ/l and 15.6 MJ/l for biodiesel. The energy value of mineral oil has also been reported. Anon. (2000) presented lubricant mineral oil as 38.5 MJ/l. Goering et al. (1982) designated the energy value of vegetable oils (rapeseed oil used for

hydraulics and lubrication) as 39.6 MJ/kg (density 0.912 kg/l). In this study rapeseed oil was taken as representative of vegetable oils. Synthetic oils are usually produced from vegetable oil bases, with only the »holder« (usually alcohol) of the fatty acid changed (Våg et al. 2000). Therefore, the same energy value (39.6 MJ/kg by density 0.912 kg/l) may be assumed for synthetic oils. Våg et al. (2000) presented energy consumption during the production of various lubrication oils as follows: mineral oil 45 MJ/l, synthetic ester 22 MJ/l and rapeseed oil 12 MJ/l. The energy audit of the cableway operation phase in MJ/m3 of wood production was done as the sum of: Þ Energy content of the fuel plus energy used in its production. The energy inputs were calculated as follows (listed respectively): mineral diesel fuel as 36.14 + 4.5 = 40.64 MJ/l and rape methyl ester as 33.1 + 15.6 = 48.70 MJ/l. Þ Energy content of oils plus energy used during their production. In the current study, these energy inputs were calculated as follows (listed respectively): vegetable oil as 36.1 + 12 = 48.1 MJ/l, synthetic oil as 36.1 + 22 = 58.1 MJ/l and mineral oils as 38.5 + 45 = 83.5 MJ/l. Exhaust emissions generated from the fuel were calculated as a sum of emissions produced by fuel combustion (Efc) and emissions produced during the fuel production, transport and distribution (Efp). With fuels that are products of photosynthesis in which plants assimilate carbon dioxide from the atmosphere, the total balance is calculated without the share of CO2 assimilated in this way. Anon. (2002) informs in the section on greenhouse gas balances that the fossil carbon content in RME amounts to 3.6% and the biomass carbon content is 69.7%. The calculated exhaust emissions resulting from fuel combustion (Efc) take into account the energy content of fuel, emission factors related to the engine output power, and the thermal efficiency of the fuel combustion process. The calculation was made using the below formula: Efc = Fc ´ Ef ´ Cv ´ Te

(1)

Where: Efc Exhaust emissions from fuel combustion, g/FU Fc Fuel consumption, l/FU Ef Emission factor, g/MJ of engine output Cv Calorific value, MJ/l Te Thermal efficiency Emission factors used for the calculation were those of wheel tractors (Table 2), only the calculation of CO2 emissions was made with the emission factor Croat. j. for. eng. 33(2012)1

Energy Use of and Emissions from the Operation Phase of a Medium Distance System (79–88)

at 263 g/MJ of engine output adopted from Athanassiadis (2000). The calculation of emissions generated during the fuel production, transport and distribution (Efp) was based on the fuel energy content and emission factors. Efp = Fc ´ Ef ´ Cv (2) Where: Efp Emissions generated in the phase of extraction, production, transport and distribution, g/FU Fc Fuel consumption, l/FU Ef Emission factor, g/MJ of engine output Cv Calorific value, MJ/l The emission factors used were those holding for Austria (Table 3). Only the emission factor of 0.0862 used for HC was adopted from Athanassiadis (2000). Emission load related to the consumption of oils was calculated as a sum of emissions emanated in the production of oils (Eop) and emissions generated in the reprocessing of used oils for the purposes of combustion (Eor). Emissions arisen in production were calculated on the basis of emission factors adopted from Ragnarsson (1994) and Marby (1999), see Table 4. Emissions generated in the transport and reprocessing of used oils for the purposes of combustion were calculated on the basis of emission factors adopted from Lenner (1990) and from Stripple and Wennsten (1997), see Table 5.

Table 4 Total emissions from oil production phase, g/l (Ragnarsson 1994; Marby 1999) Tablica 4. Ukupna emisija iz proizvodnje ulja, g/l (Ragnarsson 1994, Marby 1999) RBO MBO

CO2 747.25 260.92

CO 1.1294 0.077

HC 0.9288 2.64

NOX 5.6169 2.662

PM 0.315 0.31

RBO – rapeseed based oils – Ulje uljane repice MBO – mineral based oils – Mineralno ulje

Table 5 Total emissions from oil transport and reprocessing, g/l (Lenner 1990; Stripple and Wennsten 1997) Tablica 5. Ukupna emisija iz transporta i prerade ulja, g/l (Lenner 1990, Stripple i Wennsten 1997) Transport Prijevoz Reprocessing Prerada Total Ukupno

CO2

NOX

20.4

0.09

0.022

0.27

0.01

64.1

0.01

0.0001

0.13

0.01

84.5

0.1

0.0221

0.4

0.02

Croat. j. for. eng. 33(2012)1

Radomír Klva~ et al.

Emission load by oil production (Eop) was calculated on the basis of oil consumption data and on the basis of emission factors as: Eop = Oc ´ Ef Where: Eop Emissions emanated in the production of oils, g/FU Oc Oil consumption, l/FU Ef Emission factor, g/l

(3)

Emission load from the transport and reprocessing of used oils for combustion was calculated on the basis of emission factors and oil consumption. Emission load from the transport for combustion was calculated only in oils used for this purpose. Eor = Oc ´ Ef Where: Eor Emissions emanated during transport and reprocessing, g/FU Oc Oil consumption, l/FU Ef Emission factor, g/l

(4)

3. Results – Rezultati Values calculated on the basis of one-year measurement were as follows: Þ Productivity: 6 000 m3/year Þ Fuel consumption: 1.2 – 1.4 l/m3 Þ Gear oil consumption: 6.7 l/1000 m3 Þ Engine oil consumption: 6.7 l/1000 m3 Þ Consumption of lubricants: 1.7 kg/1000 m3 Þ Greasing spray: 1 l/1000 m3 Total energy consumed during the operation phase in the form of fuels and lubricants, including the energy required for their production, transport and distribution was calculated for two scenarios. With the use of minimum values (scenario 1) and maximum values (scenario 2) the energy consumption was 50 MJ/m3 and 58 MJ/m3, respectively. The highest share in total energy use was that of the fuel – ca. 98%. The total energy use by consumed fuel was calculated at 48.8 MJ/m3 for scenario 1 (fuel consumption 1.2 l/m3) and 56.9 MJ/m3 for scenario 2 (fuel consumption 1.4 l/m3), respectively. Energy use of 556.7 MJ/1000 m3 is associated with gear oil consumption. Since the used engine oil was of semi-synthetic character, there were two scenarios of calculation, according to the ratio of mineral and synthetic components in the oil. Energy consumption at a mineral-to-synthetic ratio of 80:20 and 35:65 was calculated to be 522.8 MJ/1000 m3 and 446.6 MJ/1000 m3, respectively. Energy use for lubricants was calculated at 149.6 MJ/1000 m3. Energy con-

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Energy Use of and Emissions from the Operation Phase of a Medium Distance System (79–88)

Table 6 Emissions generated from fuel consumption, g/m3 Tablica 6. Emisija nastala potro{njom goriva, g/m3 Scenario 1 – Slu~aj 1. Efc Diesel Efp Diesel Total Diesel Efc RME Efp RME Total RME Total RME*

CO2 4510.27 294.90 4805.17 4510.27 1187.63 5697.90 1420.59

CO 47.41 0.24 47.65 32.71 1.43 34.14 3.12

HC 1.82 3.74 5.56 0.36 1.27 1.63 1.29

NOX 77.09 1.70 78.79 94.82 8.18 103.00 103.00

Scenario 2 – Slu~aj 2. PM 8.19 0.05 8.24 6.31 0.40 6.71 6.71

CO2 5261.98 344.05 5606.03 5261.98 1385.57 6647.55 1657.35

CO 55.31 0.28 55.59 38.16 1.67 39.83 3.65

HC 2.13 4.36 6.49 0.43 1.48 1.91 1.50

NOX 89.95 1.98 91.93 110.64 9.55 120.19 120.19

PM 9.56 0.06 9.62 7.36 0.46 7.82 7.82

Scenario 1: Fuel consumption 1.2 l/m3 – Slu~aj 1: Potro{nja goriva 1,2 l/m3 Scenario 2: Fuel consumption 1.4 l/m3 – Slu~aj 2: Potro{nja goriva 1,4 l/m3 Efc RME is calculated on the basis of emission increase or decrease between RME and EC3 adopted from Athanassiadis (2000) Efc RME izra~unat na osnovi pove}anja ili smanjenja emisije izme|u RME i EC3 iz Athanassiadis (2000) Efp RME calculated on the basis of emission factors adopted from Ragnarsson (1994) – Efp RME izra~unat na osnovi faktora emisije prema Ragnarsson (1994) RME* calculated emissions which originate only from the fossil sources – RME* izra~unate emisija samo iz fosilnih goriva

Table 7 Emissions generated from the consumption of lubricants (g/1000 m3) Tablica 7. Emisija nastala potro{njom maziva, g/1000 m3 Scenario 1 – Slu~aj 1. Eop Eor Total

CO2 4885.88 1132.30 6018.18

CO 2.66 1.34 4.00

HC 40.55 0.30 40.84

Scenario 2 – Slu~aj 2. NOX 47.16 5.36 52.52

PM 5.04 0.27 5.31

CO2 6352.17 1132.30 7484.47

CO 5.83 1.34 7.17

HC 35.39 0.30 35.69

NOX 56.07 5.36 61.43

PM 5.05 0.27 5.32

Scenario 1: Fully mineral gear oils, semi-synthetic engine oil (mineral-to-vegetable ratio 80:20) and fully mineral lubricants Slu~aj 1.: Mineralna motorna ulja, polusinteti~ka motorna ulja (omjer mineralnih i biljnih ulja 80 : 20) i mineralna maziva Scenario 2: Fully mineral gear oils, semi-synthetic engine oil (mineral-to-vegetable ratio 35 : 65) and fully mineral lubricants Slu~aj 2.: Mineralna motorna ulja, polusinteti~ka motorna ulja (omjer mineralnih i biljnih ulja 35 : 65) i mineralna maziva

sumption from the greasing spray was calculated at 78.4 MJ/1000 m3. The calculation of emission load on environment was made separately for emissions emanated from the use of fuels and for emissions arisen from the use of oils. In both cases the calculation was made for two scenarios. The scenarios in fuels were established according to fuel consumption, i.e. scenario 1 with a minimum consumption (1.2 l/m3) and scenario 2 with a maximum consumption (1.4 l/m3). RME can be used as an alternative fuel and therefore a calculation was carried out of emissions emanated in using RME, too. As to the use of diesel oil, it can be stated that all emissions originated from fossil sources. In the case of RME, however, a certain amount of emissions originates from renewable sources and therefore, emissions from fossil sources were calculated for the use of RME (in tables designated as RME*). Scenarios for oils were set up according to different types of oils used, i.e. scenario 1 is based on using fully mineral gear oils, semi-synthetic engine

oil with ratio 80:20 and mineral lubricants, while scenario 2 is based on using fully mineral gear oils, semi-synthetic engine oil with the ratio 35:65 and mineral lubricants. The minimum total CO2 emission load on environment by cableway operation was determined at 4.8 kg/m3 of wood extracted from stump to roadside in case of scenarios most favorable regarding emissions. Detailed calculated emissions associated with the consumption of fuels and the consumption of oils and lubricants are presented in Table 6 and Table 7, respectively.

4. Discussion and Conclusions Rasprava i zaklju~ci Energy and emissions generated from oil consumption are almost irrelevant compared to energy and emissions related to fuel consumption. Sheehan et al. (1998) enumerated the amount of energy used and emissions in using fuels based on Croat. j. for. eng. 33(2012)1

Energy Use of and Emissions from the Operation Phase of a Medium Distance System (79–88)

Radomír Klva~ et al.

Table 8 Inputs of primary energy for production, transport and distribution of diesel-based fuels and SME Tablica 8. Ulo`ena energija za proizvodnju, prijevoz i distribuciju dizelskih i biolo{kih goriva Stage – Faza proizvodnje Domestic production of diesel, U.S.A. – Doma}a proizvodnja dizela, SAD Production abroad – Inozemna proizvodnja dizela Transport of diesel from domestic resources – Prijevoz dizela iz doma}ih izvora Transport of diesel from foreign resources – Prijevoz dizela iz stranih izvora Refining – Rafiniranje Fuel transport – Prijevoz goriva Total – Ukupno Soy production – Proizvodnja soje Soy transport – Prijevoz soje Soy pressing – Prerada soje Soy oil transport – Prijevoz sojina ulja Soy conversion to SME – Proizvodnja sojina metil estera SME transport – Prijevoz SME Total – Ukupno diesel and soy methyl ester (SME) in U.S.A. and found out that in using classical extraction and refining techniques an investment of additional 1.2 MJ of primary energies is required per each 1 MJ of energy from diesel-based fuels and additional 0.311 MJ per each 1 MJ SME (see Table 8). The emission load on environment from the fossil sources is markedly lower with methyl esters (RME and/or SME), the fact speaking for their preferred use. The question, however, of their practical application as related to engine functionality and service life, remains unanswered. Energy use of fully mechanized technologies was calculated by Athanassiadis et al. (2000) and Klvac et al. (2003). The use of energy per FU is considerably lower in cable transport, as a result of the lower consumption of fuels and lubricants per FU. The operation phase of the life cycle is the part with the greatest share in total energy and emission requirements. Generally, the issue of energy and emissions from forest operation has been widely discussed in Karjalainen et al. (2001) study, made as part of COST Action E9. In detail, Schwaiger and Zimmer (2001) built up their study on 0.9 kg/m3 cableway fuel consumption, which is lower compared to the results obtained in this study. Also the emission factors are slightly different. Moreover, it is difficult to identify from which source the emission factors were adopted and whether the emission factors cover both combustion and production, respectively. However, usCroat. j. for. eng. 33(2012)1

Inputs of primary energies, MJ/MJ Ulo`ena energija, MJ/MJ 0.5731 0.5400 0.0033 0.0131 0.0650 0.0063 1.2007 0.0656 0.0034 0.0796 0.0072 0.1508 0.0044 0.3110

% of inputs – % ulo`ene energije 47.73% 44.97% 0.28% 1.09% 5.41% 0.52% 100% 21.08% 1.09% 25.61% 2.31% 48.49% 1.41% 100.00%

ing the same average fuel consumption, the amount of emission produced by cableway system would be comparable. The productivity of cableways is significantly affected by felling methods, possible pre-bundling and by the number of choker setters as published by Visser and Stampfer (1998). These authors presented a markedly improved productivity of cableways (30 – 40 %) as compared with the power saw if the felling is made by harvester and if the logs are pre-bundled. As to the number of choker setters they concluded that in sites prepared in this way it is useful to have only one choker setter. The study was made both in deciduous and in coniferous stands. The employment of harvester technologies for logging operations in broadleaved stands is unsubstantiated in the conditions of the Czech Republic and results in considerable problems. This is why a lower energy consumption and emission load for using harvester in logging can be expected according to Visser and Stampfer (1998) only with the cableway working in spruce stands. Fuel consumption was measured in main felling operations. Berg (1997) studied the environment load with fossil fuels at different forest operations. He found that as compared with the clear felling, the share of emissions is higher by 10% and 20% in felling and skidding operations, respectively, in the shelterwood system. The calculations suggest that fuel consumption is by about 10% higher in the shelterwood system.

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Energy Use of and Emissions from the Operation Phase of a Medium Distance System (79–88)

The amount of greenhouse gas emissions produced from alternative fuel (RME) is higher than from diesel. However, if the calculation is made only for carbon dioxide emitted from fossil sources, the negative environmental load is significantly lower. It has been calculated that the share of CO2 emissions from fully mechanized harvesting system in the national context of countries with high forest coverage such as Sweden was 1% (Athanassiadis 2000). By using methylesters in diesel engines of mechanized logging technologies, the expected considerable reduction (by up to 70%) of CO2 emissions originating from fossil sources will be accompanied by a 30% increase of NOx emissions.

Acknowledgements – Zahvala This paper was prepared within the framework of research projects of the Ministry of Education of the Czech Republic »Forest and Wood. Support to a functionally integrated forest management.«, MSM 6215648902 and of the Ministry of Agriculture of the Czech Republic »Sophisticated model for nature – friendly timber haulage evaluation«, QH71159. The authors also wish to express their thanks to contractors for enabling the collection of data.

5. References – Literatura AGO – Australian Greenhouse Office, 2000: URL: http:// www.greenhouse.gov.au/transport Altin, R., Çetinkaya, S., Yücesu, H. S., 2001: The potential of using vegetable oil fuels as fuel for diesel engines, Energy Convers Manage. 42 (5): 529–538. Anon., 1994: Perspektivy pou`ití biologicky odbouratelných maziv a paliv – sborník referátù (Perspectives of use biodegradable fuels and grease). Brno. Mendel University of Agriculture and Forestry Brno. 61 pp. (In Czech.) Anon., 2000: Benzina, a.s. (Fuel and Oil Company) Brochure information. (In Czech.) Anon., 2002: Energy and greenhouse gas balances of biofuels´ production chain in France. Executive summary. Agrice, France. Available from http://www.ademe.fr/partenaires/agrice/publications/ documents_anglais/synthesis_energy_and_greenhouse_ english.pdf Anyon, P., 1998: Liquefied Petroleum Gas as an Automotive Fuel – An Environmental and Technical Perspective, Ninderry, Queensland, for the Australan Liquefied Petroleum Gas Association, Redfern, NSW. Athanassiadis, D. 2000: Energy consumption and exhaust emissions in mechanised timber harvesting operations in Sweden. Sci. Total Environ. 255 (1–3): 135–143.

Berg, S., 1996: Emisioner till luft från fossila bränslen i svenskt skogsbruk En inventering för LCA av träprodukter. Tretek, Report p9601004. ISRN: TRÄTEK-R-96/004-SE. (In Swedish) Berg, S., 1997: Some aspects of LCA in the analysis of forestry operations. J. Cleaner Prod. 5(3): 211–217. Calais, P., Sims, R., 2006: A Comparison of Life-Cycle Emissions of Liquid Biofuels and Liquid and Gaseous Fossil Duele in the Transport Sector. Mudroch University, Perte, Australia. URL: http://www.biodiesel.org.au/Documents/Calais_Sims_Life%20cycle%20comparison.pdf Davison, P., Lewis, C. A., 1999: Fuel and energy production. Ed. Hickman, A.J. Methodology for calculating transport emissions and energy consumption, Part E. Projekt report SE/491/98. Transport Research Laboratory, Crowthorne, UK. 362 pp. Furuholt, E., 1995: Life cycle assessment of gasoline and diesel. Resour. Conserv. Recycl. 14 (3–4): 251–263. Goering, C. E., Schwab, A. W., Daugherty, M. J., Pryde, E. H., Heakin, A. J., 1982: Fuel properties of eleven vegetable oils. Trans. ASAE 25 (6): 1472–1477. Grägg, K., 1994: Effects of environmentally classified diesel fuels, RME and blends of diesel fuels and RME on the exhaust emission. MTC, Report 9209B, 44 pp. Grägg, K., 1998: Emissions from use of RME compared to environmental class 1 diesel fuel in a HD vehicle. MTC, Report 98/9, 26 pp. Grägg, K., 1999: Emissions from two truck engines and two off-road engines. MTC, Report 6806, 14 pp. Hamilton, B., 2000: Automotive Gasoline FAQ. URL: http:// www.cs.ruu.nl/wais/html/nadir/autos/gasoline-faq/.html Karjalainen, T., Asikainen, A., 1996: Greenhouse gas emissions from the use of primary energy in forest operations and long-distance transportation of timber in Finland. Forestry 69(3): 215–228. Karjalainen, T., Zimmer, B., Berg, S., Welling, J., Schwaiger, H., Finér, L., Cortijo, P., 2001: Energy, carbon and other material flows in the Life Cycle Assessment of forestry and forest products. Achievements of the working group 1 of the COST action E9. European Forest Institute, Torikatu 34, Finland. ISBN 952-9844-92-1, ISSN 1455-6936. 68 pp. Klvac, R., Ward, S., Owende, P., Lyons, J., 2003: Energy Audit of Wood Harvesting Systems. Scand. J. For. Res. 18(2): 176–183. Lenner, M., 1993: Energiförbrukning och avgasemissioner för olika transporttyper. VTI, Meddelande Nr 718, 44 pp. (In Swedish) Lewis, C. A., 1997: Fuel and energy production emission factors. ETSU Report No. R112. Didcot, United Kingdom. 57 pp. Lide, D. et al., 1999: CRC Handbook of Chemistry and Physics, 79th Edition, Boca Raton, Florida. Croat. j. for. eng. 33(2012)1

Energy Use of and Emissions from the Operation Phase of a Medium Distance System (79–88) Marby, A., 1999: Life-cycle analysis on base oils. Kemiingenjörsutbildningen, KTH-Ingenjörs-skolan, Examensarbete, 35 pp. (In Swedish, with English abstract) Mc Donnell, K. P., 1996: Semi-refined rapeseed oil (SRO) as a diesel fuel extender for agricultural equipment. Doctoral thesis. University College Dublin, Agricultural and Food Engineering Department, Dublin, 288 pp. Ragnarsson J. O., 1994: RME och Diesel MK1 – en jämförelse av miljöpåverken från framställning till användning. Celsius Materialteknik, Report M4720301.122, 102 pp. (In Swedish) Sambo, S. M., 1997: Fuel consumption estimates for typical coastal British Columbia forest operations. Forest Engineering Research Institute of Canada, Technical note TN-259, 4 pp. Sheehan, J., Camobreco, V., Duffield, J., Graboski, M., Shapouri, H., 1998: An Overview of Biodiesel and Petroleum Diesel Life Cycles. NREL, Golden, Colorado. Stripple, H., Wennsten J., 1997: Energi-, resurs- och emissionsanalys med livscykelanalysmetodik av ett bilåtervinningssystem; En studie av Ecrisprojektet. IVL, Raport B1251, 52 pp. (In Swedish, with English abstract).

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Schwaiger, H., Zimmer, B., 2001: A comparison of fuel consumption and greenhouse gas emissions from forest operations in Europe. In: Risto Päivinen (ed.) Energy, carbon and other material flows in the life cycle assessment of forestry and forest products – achievements of the working group 1 of the COST action E9. Joensuu: European Forest Institute. Discussion Paper 10, 33–53 pp. USEPA, 1985: Compilation of Air Pollutant Emission Factors, Volume 2: Mobile Sources, fourth edition, A-42. Section 2.7 Heavy Duty Construction Equipment. United States Environmental Protection Agency, Office of Air and Radiation, Office of Mobile Sources Test and Evaluation Branch Ann Arbor, Michigan, USA. Våg, C., Marby, A., Kopp, M., Furberg, L., Norrby, T. A., 2000: Comparative life cycle assessment (LCA) of the manufacturing of base fluid for lubricants. Statoil Lubricants Research & Development, P.O. Box 194, SE-149 22 Nynäshamn, Sweden. Visser, R., Stampfer, K., 1998: Cable Extraction of Harvester-Felled Thinnings: An Austrian Case Study. Journal of Forest Engineering. 9(1):39–46.

Sa`etak

Potro{nja energije i emisija {tetnih plinova pri radu ì~are Kako stakleni~ki plinovi zna~ajno utje~u na klimatske promjene, smanjenje je njihove emisije jedan od primarnih ciljeva okoli{ne politike Europske unije. Kako bi se ispunili zadani cilj, potrebno je ponajprije pove}ati udio energije dobivene iz obnovljivih izvora, gdje nema emisije CO2 iz fosilnih goriva. U dana{nje vrijeme svaki je proizvod optere}en s odre|enim udjelom primarnih fosilnih goriva te stoga i s odre|enom emisijom stakleni~kih plinova. Utjecaj bilo koje tehnologije ili proizvoda na okoli{ moè se procijeniti pomo}u metode ìvotnoga ciklusa, koja definira ulazne i izlazne parametre te njihov utjecaj na okoli{ (norma ISO 14040-2). U radu je opisana energetski najzahtjevnija faza ìvotnoga ciklusa proizvoda, na primjer faza proizvodnje. Cilj je ovoga rada bio odrediti koli~inu energije potrebne za izno{enje jedinice proizvoda (m3) pomo}u ì~are te odrediti koli~inu emisije i utjecaj na okoli{. Istraìvane su ì~are Larix 550 i Larix 3T, koje su kao transportno i pogonsko sredstvo koristile poljoprivredni traktor. @i~ara Larix 550 napravljena je kao nadogradnja poljoprivrednoga traktora (ZETOR 8540, 9540, 10540 ili bilo kojega sli~noga (NEW HOLLAND, SAME, STEYER, JOHN DEERE), {to joj pruà odre|ene prednosti pri kretanju po terenu te olak{ava posao postavljanja ì~are za rad. @i~are se mogu koristiti prilikom svih na~ina rada, pri privla~enju niz brdo (100 – 550 m), privla~enju uz brdo te privla~enju na ravnom. Ovisno o svojstvima terena, ì~ara moè biti postavljena s beskona~nim nosivim uètom ili s uètom za privla~enje. Osnovne su tehni~ke zna~ajke ì~are: vu~na sila 35 kN, doseg uèta 550 m, nosivost 2 t, vrijeme postavljanja 4 – 8 sati. @i~ara Larix 3T razvijena je na principu ì~are Larix 550 s beskona~nim nosivim uètom, a moè se postaviti i na prednju i na stra`nju trozglobnu poteznicu traktora. Model 3T razlikuje se od modela 550 u poja~anoj nosivoj strukturi, pojednostavljenom dizajnu i upravljivosti, u ve}im bubnjevima, pove}anoj nosivosti (3 t) i pove}anom dosegu (850 m). Energetska bilanca sadrì energetski sadràj i energiju potrebnu za proizvodnju goriva i maziva. Potro{nja goriva koja je se mjerila kroz jednu godinu iznosila je 1,2 – 1,4 l/m3, potro{nja je ulja za opremu iznosila 6,7 l/1000 m3, potro{nja je ulja u motoru iznosila 6,7 l/1000 m3, tokom istraìvanja potro{eno je i 1,7 kg/1000 m3 te 1 l/1000 m3 spreja za podmazivanje. Godi{nja je proizvodnja iznosila 6000 m3. Potro{nja je energije izra~unata za dva slu~aja, gdje su u prvom slu~aju kori{tene minimalne vrijednosti, a u drugom slu~aju maksimalne vrijednosti. Potro{nja energije u istraìvanom razdoblju iznosila je za prvi slu~aj 50 MJ/m3, a za drugi slu~aj 58 MJ/m3. Na osnovi potro{nje goriva i maziva u radu je odre|ena koli~ina emisije s posebnim osvrtom na

Croat. j. for. eng. 33(2012)1

Radomír Klva~ et al.

Energy Use of and Emissions from the Operation Phase of a Medium Distance System (79–88)

emisiju stakleni~kih plinova (tablice 6 i 7). Tako|er je istra`ivana i potro{nja energije ovisno o omjeru smjese ulja koje je kori{teno za stroj i opremu; tako su kori{tena polusinteti~ka ulja omjera smjese 80 : 20 i 35 : 65. Energetska je potro{nja iznosila 556,7 MJ/1000 m3 za ulje 80 : 20, a za ulje 35 : 65 energetska je potro{nja iznosila 446,6 MJ/1000 m3. Energetska je potro{nja za maziva iznosila 149,6 MJ/1000 m3, a za sprej za podmazivanje 78,4 MJ/1000 m3. U tablicama 6 i 7 izra~unate su emisije za dizelsko gorivo i poslije primijenjeno biogorivo uljane repice (RME). Tako|er je izra~unata emisija koja potje~e od fosilnih goriva. Uporabom se biogoriva uljane repice koli~ina emisije CO2 iz fosilnih goriva mo`e smanjiti za 3,4 kg/m3 privu~enoga drva. Klju~ne rije~i: emisija stakleni~kih plinova, energetska bilanca, potro{nja goriva, potro{nja maziva

Authors’ addresses – Adresa autorâ:

Received (Primljeno): June 8, 2011 Accepted (Prihva}eno): February 07, 2012

Asocc. Prof. Radomír Klva~ e-mail: klvac@mendelu.cz Mr. Radek Fischer e-mail: xfische3@node.mendelu.cz Assoc. Prof. Alois Skoupý, e-mail: skoupy@mendelu.cz Mendel University in Brno Faculty of Forestry and Wood Technology Department of Forest and Forest Products Technology Zemedelska 3 613 00 Brno CZECH REPUBLIC Croat. j. for. eng. 33(2012)1

Original scientific paper – Izvorni znanstveni rad

Potential Mechanisms for Co-operation between Transportation Entrepreneurs and Customers: A Case Study of Regional Entrepreneurship in Finland Palander Teijo, Vainikka Mika, Yletyinen Antti Abstract – Nacrtak The objectives of this study were to investigate how to increase co-operation in the regional entrepreneurship approach of wood transportation and facilitate the ongoing outsourcing of wood-procurement responsibilities in the Finnish forest industry. We examined co-operation between transportation entrepreneurs (suppliers) and between suppliers and the forest industry (customers). A questionnaire was sent to wood transportation entrepreneurs working in the wood-procurement network of the customers. The entrepreneurs felt that the most interesting form of consortium between suppliers, which would let them respond better to outsourcing, would be the formation of a joint venture responsible for sales and marketing of their services. Such a company would develop an overall contract with each customer, and then each shareholder in the joint venture would sign their own contracts with the venture to share the work. All transactions would be based on invoicing instead of the current salary-based approach. However, entrepreneurs did not believe that their profitability would increase by expanding their responsibilities in the current entrepreneurial environment. If the aim of co-operation is to outsource the wood transportation function, decision-makers in the Finnish forest industry should modify the current environment so that larger, more organized consortia of wood suppliers would become more profitable than they presently are in the regional entrepreneurship approach. Keywords: Wood procurement, Outsourcing, Regional entrepreneurship, Networking

1. Introduction – Uvod Almost all of the wood used by the Finnish forest industry is transported by trucks at some stage of the wood-procurement network, from the forest to the mill. Currently, approximately 850 Finnish wood transportation companies own about 1700 trucks and employ about 2600 drivers. Three-quarters of these wood transportation companies are small; families own one or two trucks, which usually deliver more than 90% of wood to a single customer. Nowadays, three of the largest customers (»Stora Enso«, »UPM«, and »Metsäliitto«) dominate the wood-procurement field, with a combined market share of about 90% of wood that is transported in Finland. Traditionally, wood-procurement organizations sign direct transportation contracts with each transCroat. j. for. eng. 33(2012)1

portation company. These contracts have been used to strictly define the transportation operations that the entrepreneurs are responsible for. Traditionally, most of these contracts have been with employees of the wood-procurement organizations, and specified a fixed salary for the trucker. More recently, the forest industry has begun trying to outsource many of its operations, including wood transportation, in an effort to reduce its operating costs. However, this transition is only partially complete, and the current form of transportation entrepreneurship still retains many features of the traditional system. As a result, the kind of invoice-based (rather than salary-based) entrepreneurship that is typical of outsourced work markets has not yet become possible. In any outsourced business environment, entrepreneurs would invoice their customers for the work that they actual-

T. Palander et al. Potential Mechanisms for Co-operation between Transportation Entrepreneurs and Customers ... (89–103)

ly do, rather than receiving fixed payments as part of an employment contract (Beimborn et al. 2005). However, the current form of co-operation in transportation prevents this kind of invoicing. In the current operating environment, cost-efficiency is based on a large amount of the salary-based work performed by many small-scale entrepreneurs and members of their families. This environment provides relatively low direct transportation costs. However, it prevents the economies of scale that would become possible with large-scale entrepreneurship. The costs of a Finnish transportation company have increased by 20% from year 2005 to 2010 (Fig. 1), and are shown in the financial statements as four main cost sources: purchases (for example parts, maintenance, fuel) wages (for example wages, pension contributions, indirect employee costs), other fixed costs (for example upkeep, rent, insurances), and capital costs (for example interest, depreciation). If the management costs are considered as an indicator of outsourcing, it seems that nothing has happened since 2005 that could be interpreted as an increase of outsourcing. In the present study, wood suppliers were considered to be the transportation entrepreneurs, and their customers to be the wood-procurement organizations in the forest industry. Customers incur transaction costs caused by the need to exactly specify the transportation functions. The concept of transaction cost to be used is strictly linked to the idea of the cost of social division of labor (Coase 1998; Demsetz 2003; Bertolini and Giovannetti 2006). In this study, these

transaction costs are described for the wood-procurement organizations that manage and control the transportation function in the wood-procurement network (Fig. 2). According to Williamson (1981), the determinants of transaction costs are frequency, specificity, uncertainty, limited rationality, and opportunistic behavior. Through transaction cost minimization and knowledge exchange, networking can lead to higher performance of organization as a tool of regional and industrial policy (Andreosso-O’Callaghan and Lenihan 2008). Globalization of the forest industry has required steadily increasing efficiency and decreasing staff size in the industry’s wood-procurement network in recent decades. If the wood procurement organizations keep growing leaner, it may become impossible to apply the traditional contracting model because the number of managers of the forest industry is too small to perform the work needed to manage and control the transportation function. In this changing entrepreneurial environment, the forest industry is attempting to improve its cost-effectiveness by offering transportation contractors extended entrepreneurship agreements that increase their responsibilities (Högnäs 2000; Palander et al. 2006). Actually, extended entrepreneurship is the first stage of ongoing process from contracting model of wood procurement network to outsourcing model of wood supply network. Fig. 2 shows that, after determining internal transaction costs separately in institutions and wood procurement companies, a decision can be made »whether to outsource

Fig. 1 Change of timber haulage truck’s cost index from 2005 (left) to 2010 (right) according to K. Palojärvi (personal communication June 15, 2010) Slika 1. Promjena indeksa tro{kova kamiona za prijevoz drva od 2005. (lijevo) do 2010. (desno) prema K. Palojärvi (osobna komunikacija, 15. lipnja 2010) 90

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Potential Mechanisms for Co-operation between Transportation Entrepreneurs and Customers ... (89–103) T. Palander et al.

Fig. 2 Transaction model that shows institutions and market as a potential form of outsourcing to organize economic transactions. E.g., when the external transaction costs of the wood procurement company A (ETC) are higher than the internal transaction costs (ITC), the company can grow (left side). If the internal transaction costs of the wood procurement company A are higher than the external transaction costs the company can be downsized by outsourcing (right side) Slika 2. Model koji prikazuje institucije i trì{te kao potencijalni oblik izdvajanja u organizirane ekonomske transakcije. Kada su vanjski tro{kovi transakcije (ETC) poduze}a za dobavljanje drva A ve}i od internih tro{kova transakcije (ITC), poduze}e moè rasti (lijeva strana). Ako su interni tro{kovi transakcije poduze}a A ve}i od eksternih tro{kova, transakcija se poduze}a moè smanjiti izdvajanjem dijela poslova (desna strana) or not to outsource wood transportation function« based on external transaction costs of the wood procurement company. For the Finnish forest industry the extended entrepreneurship is a logical consequence of the outsourcing of business functions that is becoming increasingly common in international markets. Based on a theory of transaction costs, outsourcing could potentially reduce the total costs of procuring raw materials at the mill (Williamson 1975, 1985). If the theory is correct, the forest industry’s overall cost-effectiveness and international competitiveness would improve. Regional entrepreneurship is one form of extended entrepreneurship that emphasizes co-operation between the wood supplier and the customer (Palander et al. 2006). In wood transportation sector regional entrepreneurship is a new thing, even though earth-moving and road-construction entrepreneurs have used this approach for decades. In a typical regional entrepreneurship application, the wood-procurement organization would sign transportation contracts with fewer entrepreneurs, each responsible for a larger area (a »region«). These extended contracts would include transportation tasks that are larger and more diverse, and that include more responsiCroat. j. for. eng. 33(2012)1

bilities, than in conventional contracts. A regional entrepreneur can fulfill their contract commitments either by working alone or by co-operating with other entrepreneurs. The latter form of co-operation can occur via different forms of consortium: Þ Subcontracting, in which one entrepreneur buys services from other entrepreneurs, acting as sub-contractors, Þ Joint venture, in which a group of companies (the consortium) jointly signs a contract with a customer, and then consortium members share the payments for the work on a pre-determined basis, Þ Joint venture for sales and marketing, in which the joint venture signs contracts with customers, and shareholders sign contracts with the joint venture (with all monetary transactions based on invoicing rather than salaries), Þ Merger, in which the separate companies form a single new company, with the original equipment either transferred or sold to that company; the entrepreneurs then become shareholders in the new company and close the old companies. Shareholders work for this company and select a manager for the merged company,

T. Palander et al. Potential Mechanisms for Co-operation between Transportation Entrepreneurs and Customers ... (89–103)

Þ Acquisition of another company, in which the seller transfers their equipment to the buyer, and subsequently works for the buyer. Regional entrepreneurship has been adopted slowly by customers. Although »Stora Enso« is now beginning to investigate extended entrepreneurship contracts, several entrepreneurs working for »UPM-Kymmene« and »Metsäliitto« Cooperative have already signed such contracts. To advance this development, transaction costs can be used as a decision support. However, transaction costs are difficult to calculate, which may cause errors and uncontrolled variation in the data. Recently, Bertolini and Giovannetti (2006) have examined the important role played by the co-operative movement and co-operative firms, which allowed the reduction of transaction costs. Moreover, the networking literature takes a view that co-operation is an essential component of new-firm generation and growth (Jack et al. 2008). Before calculation transaction costs, a survey could be used as a study method to learn the opinions of stakeholders about the co-operation required by the operational environment of consortium, regional entrepreneurship, extended entrepreneurship and outsourcing. Studies suggest that outsourcing can be promoted by increasing the size of contracts, extending the number of tasks and responsibilities included in the contract, and giving entrepreneurs more freedom of action, as proposed by Högnäs (2000). In wood transportation these actions require co-operation among entrepreneurs to form consortia, which are potentially more profitable. Palander and Väätäinen (2005) and Palander et al. (2006) noted that, based on current trend, there will be fewer, larger transportation consortia in the future, with increased networking among them. Networks can be vital living organisms, changing, growing and developing over time. Therefore, networks will create the entrepreneurial environment as suggested by Jack et al. (2008). The present transportation functions are also becoming differentiated and focused in different ways so that the wood-procurement network will have new actors, including workers who act as coordinators between the current organizations. Furthermore, Bengtsson and Kock (2000) have noted that competition and co-operation can exist simultaneously within a network of organizations. In the study conducted by Ala-Fossi et al. (2004), service suppliers regarded joint ventures more positively than subcontracting as a co-operation model for the outsourced activities. On the other hand, Palanderet al. (2006) found that both service suppliers and customers regarded joint ventures among transportation service suppliers as the weakest organizational alternative. These contradictory results

may have resulted from the fact that many of the entrepreneurs failed to understand the nature or implications of outsourcing. In the previous studies, comparisons of alternatives were therefore based more on images than on the actual knowledge. This lack of knowledge may have occurred because, at that time, the industry was just beginning to gain experience with regional entrepreneurship and had not yet clearly defined its needs. Entrepreneurs who have signed contracts with extended responsibilities have repeatedly identified deficiencies in current models of regional entrepreneurship. The inability to work through invoicing, because customers have not yet replaced their traditional payment model and disadvantages of the current transportation routing methods were seen as significant obstacles to the development of regional entrepreneurship. The former problem prevents the development of genuine business expertise, since if outsourcing were based on invoicing, theories would provide instruments and methods of coordination that could be applied to improve business practices (Beimborn et al. 2005; Bititci et al. 2005). Currently, it is impossible to apply these tools in Finland because wood-procurement organizations still pay entrepreneurs a piece rate according to the quantity of wood delivered. In a theory of outsourcing, regional entrepreneurship would permit invoicing rather than salary-based work. The second barrier to efficient regional entrepreneurship relates to the problem of routing. Currently, wood-procurement organizations tell each truck where to go to pick up wood. This leaves entrepreneurs little freedom to organize their own resources (time, trucks, drivers, routes), and often leads to operational inefficiencies if (for example) this prevents an entrepreneur from taking advantage of other opportunities, such as the chance to carry payload during a backhaul instead of traveling empty. For entrepreneurs, it would be beneficial to be allowed to control the volume they transport and the routing of their vehicles. This would provide many benefits both for them and for the wood-procurement organizations they serve. Benefits mentioned by entrepreneurs include group transport (i.e., the ability to group several trucks to haul a roadside inventory too large for a single entrepreneur to handle), a high vehicle utilization rate, backhauling, improved inventory control, improved control of seasonal variation in the wood supply, various synergies, and a better understanding of wood harvesting and the overall wood-procurement logistics chain (Palander and Väätäinen 2005). To permit the evolution of regional entrepreneurship and make it part of the wood-procurement network, more studies are needed to describe opportuniCroat. j. for. eng. 33(2012)1

Potential Mechanisms for Co-operation between Transportation Entrepreneurs and Customers ... (89–103) T. Palander et al.

ties for co-operation and the operational environment. Steps should also be taken to prepare for the increased co-operation of transportation entrepreneurs. Understanding the opinions (concerns and priorities) of entrepreneurs would facilitate the development of regional entrepreneurship; at a minimum, it would promote the development of current consortia of entrepreneurs by providing insights into future changes in their operating environment. For example, there may be an optimal company size in terms of profitability, as suggested by Soirinsuo and Mäkinen (2009). The results of another study suggested that transportation entrepreneurs with large company sizes were more interested in regional entrepreneurship than small entrepreneurs (Ala-Fossi et al. 2004). However, the study did not determine why the entrepreneurs of large sized companies regarded regional entrepreneurship more positively than was the case with the other transportation entrepreneurs. We speculate that this attitude may result from the greater resources available to the large companies, and their working experience in larger regions, which make the responsibility of operating on a regional scale seem less intimidating. Further, the fear of incorrect decisions leading to ineffective investments can slow the development of regional entrepreneurship during the amortization period for these investments. Our review of the research results and theories related to outsourcing and regional entrepreneurship suggests that both should be based on co-operation, but co-operation between actors requires improvement. It has been assumed that regional entrepreneurship will remain uncommon because it is not clear how to encourage co-operation between wood suppliers and between suppliers and their customers in the current changing operating environment. Therefore, the objectives of the present study were to investigate how to increase co-operation in the wood transportation operations and facilitate the ongoing outsourcing of wood-procurement responsibilities in the Finnish forest industry. To support this research, we surveyed entrepreneurs to learn their opinions about the following categories of questions: (1) What factors prevent regional entrepreneurship from becoming more common? (2) How do customers perceive regional entrepreneurship? (3) How prepared are entrepreneurs to develop co-operative agreements, and what possibilities do they see arising from these agreements? (4) Are entrepreneurs willing to form various kinds of consortia, and what are the perceived implications for their profitability? We also focused on the questions of supplier-customer relationships and transportation company size, since these are possible explanatory factors for the different opinions of respondents. Croat. j. for. eng. 33(2012)1

2. Research Data and Study Methods Podaci i metode istra`ivanja The data used in this study was obtained from Finland in 2006 using a questionnaire that was carefully tested and revised before using it to collect the research data. The survey was distributed by mail to wood transportation entrepreneurs belonging to the Finnish Transport and Logistics Association (SKAL). This association represents transportation entrepreneurs in negotiations with customers in work markets. About 410 wood transportation companies are members of the association in the study area. The target group for our survey comprised entrepreneurs who had not signed regional entrepreneurship contracts (n = 198). This group of entrepreneurs had no prior knowledge of co-operation between suppliers or between suppliers and their customers within the wood-procurement network. In total, 84 entrepreneurs returned the questionnaire, and after eliminating incorrect responses, we retained answers from 76 entrepreneurs. Consequently, the final response rate was 39%. We included four regional entrepreneurs in the results because they had just begun working under the new form of environment. Tests for non-response bias were made. According to Director of the Timber Carriers Association, our survey provided a representative sample of Finnish wood transportation entrepreneurs. On the other hand, there were a few entrepreneurs who were not members of SKAL, but their percentage of the total wood transported was sufficiently low to be irrelevant for the survey. In addition, three of these entrepreneurs worked mainly in Russia, so their data were not relevant because the target group in our study was wood transportation entrepreneurs working in Finland. We divided our questionnaire into three parts. The first part asked entrepreneurs about their current situation and obtained other background information, such as the form of the company, the form of their contract, the size of their company, and their most important customer. We used the last two parameters as the basis for grouping the transportation entrepreneurs. All respondents answered the same questions so that we could compare the answers between groups. We used the number of trucks as an indicator of the size of a respondent’s operations; we divided the entrepreneurs into three groups based on the size of their company. Out of the 76 respondents, 44 had only one truck (»small company«). Medium company (16 respondents) had two trucks, and large company (16 respondents) had three or more trucks. The biggest company had 12 trucks. The transportation entrepreneurs supplied wood to a total of eight customers, from which 6 had two

T. Palander et al. Potential Mechanisms for Co-operation between Transportation Entrepreneurs and Customers ... (89–103)

main customers and 70 entrepreneurs identified their most important customer. We divided transportation entrepreneurs into five groups based on their most important customer: »Stora Enso« was the most important customer for 25 entrepreneurs, »UPM« for 16 entrepreneurs, »Metsäliitto« for 10 entrepreneurs, and the Finnish »Forest and Park Service« for 9 entrepreneurs. The remaining 10 transportation entrepreneurs formed a group that worked for Other Customers. We found no statistically significant differences in the number of years of experience between entrepreneurs with different company sizes. However, owners of the large companies had, on average, been working as transportation entrepreneurs for a little longer (30 years) than entrepreneurs who owned medium (23 years) or small (23 years) companies. The number of working hours per week can vary greatly for entrepreneurs depending on the season, annual holidays, sick leave and time required to repair their equipment. Our survey was distributed in mid-winter and late winter, but the duration of the work week was similar in both cases (an average of 68 hours per week). We found no statistically significant differences in working time between transportation entrepreneurs of different company sizes or with different customers. In the second part of the questionnaire, we asked entrepreneurs about their attitudes towards the concept of regional entrepreneurship. To do so, we asked entrepreneurs to state their opinions about various statements using a seven-point Likert-like scale, ranging from »I fully agree« to »I fully disagree«. The third part of the questionnaire investigated the co-operation between transportation entrepreneurs by asking them to evaluate a series of statements concerning different forms of consortium, and particularly about whether they perceived these forms of consortia as interesting and likely to be feasible. This part of the survey employed »strategic gap analysis« (Ansoff 1965), and contained statements that were designed to evaluate the preparedness of entrepreneurs to choose different forms of consortium, and opportunities to do so. We also asked the entrepreneurs to estimate the truthfulness of each statement. For many of the questions, we also gave entrepreneurs an opportunity to explain their responses, and some of these responses provide possible explanations for the results. We analyzed the data using SPSS-X (SPSS Inc (1988) SPSS-X User’s Guide. 3rd ed. SPSS Inc., Chicago) in three stages. In the first stage, we summarized the background information using averages for the volume of activity and percentage shares of the response rates. The attitude results, based on the seven-

-point Likert-like scale, were analyzed based on the relative shares of answers and based on a weighted average of the responses. In the second stage, we analyzed the answers using Kendall’s rank-correlation coefficient (t). In the third stage, we studied groups of transportation entrepreneurs using nonparametric analysis of variance (the Kruskal-Wallis test) and compared these groups two at a time using the Mann-Whitney U-test. We used these tests (both based on ordinals) because the variable values (answers) did not show a normal distribution, and the tests let us test whether two independent samples (groups) came from the same population. The former test revealed whether the groups being tested were significantly different, after which we identified specific significant differences using the Mann-Whitney U-test in paired comparisons. Unless otherwise noted, we used the Mann-Whitney U-test and a significance level of p < 0.05 for all results.

3. Results – Rezultati The entrepreneurs thought that their most important customers had different opinions of regional entrepreneurship (Kruskal-Wallis). According to the entrepreneurs, »Stora Enso« was most negative about regional entrepreneurship, with a significantly smaller Likert value (3.6) than the average (5.9) for those who reported »Metsäliitto« as their most important customer, which had the most positive attitude towards regional entrepreneurship. The mean Likert value for entrepreneurs who provided wood for »Stora Enso« was also significantly smaller than the average (5.4) for the group that worked for »UPM« and the average (5.0) for the group that worked for the Finnish »Forest and Park Service«. The Likert value for the group that worked for Other Customers (4.2) was significantly smaller than the values for who that worked for »Metsäliitto« and »UPM«. The entrepreneurs believed that their most important customer should inform them better about the customer’s plans regarding regional entrepreneurship. The mean Likert value (2.6) for this statement was the lowest for entrepreneurs working for »Stora Enso« and for entrepreneurs in medium companies (2.9), and the highest for entrepreneurs working for »Metsäliitto« (3.8) and for entrepreneurs in small companies (3.4); however the differences were not statistically significant. There was a statistically significant correlation between the positive attitude of the customer towards regional entrepreneurship and the entrepreneur’s desire for more information (t = 0.324). Table 1 summarizes the responses of the entrepreneurs to our survey statements about regional Croat. j. for. eng. 33(2012)1

Potential Mechanisms for Co-operation between Transportation Entrepreneurs and Customers ... (89–103) T. Palander et al.

Table 1 Levels of agreement with the statements regarding regional entrepreneurship. 1 = Fully disagree; 2 = Disagree; 3 = Mildly disagree; 4 = Don’t know; 5 = Mildly agree; 6 = Agree; 7 = Fully agree. Entrepreneurs were divided into groups based on their company size (Small (1 truck) = S; Medium (2 trucks) = M; Large (3 or more trucks) = L) and their most important customer (»Stora Enso« = A; »UPM« = B; »Metsäliitto« = C; »Forest and Park Service« = D; Other Customers = E) Tablica 1. Razina slaganja s tvrdnjama u vezi s regionalnim poduzetni{tvom. 1 = Uop}e se ne slaèm; 2 = Ne slaèm se; 3 = Blago se ne slaèm; 4 = Ne znam; 5 = Blago se slaèm; 6 = Slaèm se; 7 = Potpuno se slaèm. Poduzetnici su podijeljeni u grupe prema veli~ini tvrtke (Mali /1 kamion/ = S; Srednji /2 kamiona/ = M; Veliki /3 ili vi{e kamiona/ = L) i najva`nijim korisnicima (»Stora Enso« = A; »UPM« = B; »Metsäliitto« = C; »[umska i parkovna slu`ba« = D; Ostali korisnici = E)

I understand what regional entrepreneurship means – Razumijem {to zna~i regionalno poduzetni{tvo Regional entrepreneurship is a favorable development for the wood transportation Regionalno je poduzetni{tvo povoljan razvoj za transport drva The forest industry is only promoting regional entrepreneurship to transfer their wood-procurement costs on to transportation entrepreneurs – [umska industrija promovira regionalno poduzetni{tvo samo radi prebacivanja svojih tro{kova dobave drva na privatne prijevoznike The bargaining position of a regional entrepreneur is significantly stronger than that of entrepreneurs with a normal salary-based contract – Pregovara~ka pozicija regionalnih poduzetnika znatno je ja~a od poduzetnika s normalnim platnim ugovorom Regional entrepreneurship will lead to overcapacity in the wood transportation Regionalno }e poduzetni{tvo rezultirati prekapacitiranjem u prijevozu drva I have enough ability to negotiate on behalf of a consortium or a joint venture Imam dovoljno sposobnosti da pregovaram u ime konzorcija ili za zajedni~ki pothvat/ulaganje I am willing to expand the area in which I operate and to take on new responsibilities to become a regional entrepreneurship Voljan sam pro{iriti podru~je rada i preuzeti nove odgovornosti da postanem regionalni poduzetnik A regional entrepreneurship would improve the cost-efficiency and profitability of the whole wood-procurement network – Reginalno }e poduzetni{tvo pobolj{ati tro{kovnu u~inkovitost i profitabilnost ukupne mre`e dobavljanja drva I have enough knowledge of long-distance transportation routing and the planning of backhauls Imam dovoljno znanja o odre|ivanju ruta i planiranju udaljenoga transporta I have enough ability to make additional use of information technology Imam dovoljno sposobnosti za dodatno kori{tenje informacijskih tehnologija I have enough ability to found a joint venture that would take care of both harvesting and transportation of wood – Imam dovoljno sposobnosti za zajedni~ki pothvat/ulaganje koji bi pokrivao pridobivanje i transport drva istodobno I have enough resources to purchase planning and data systems Imam dovoljno sredstva za kupnju sustava za planiranje i podatke I want more training in the fields of information and communications technology @elim vi{e osposobljavanje u podru~ju informacijskih i komunikacijskih tehnologija Regional entrepreneurship will become more common in the future Regionalno }e poduzetni{tvo u budu}nosti postati uobi~ajenije entrepreneurship, grouped by major customer and company size. The entrepreneurs commonly believed that the forest industry was only promoting regional entrepreneurship to pass their wood-procurement costs to the transportation entrepreneurs (mean Likert value = 6.2). The entrepreneurs who worked for »Metsäliitto« and »Stora Enso« were least likely to believe this statement (Likert values of 5.9 and 6.0, Croat. j. for. eng. 33(2012)1

A 6.0

Customer Korisnik B C D 5.4 5.8 5.0

E 5.7

Company size Veli~ina tvrtke S M L 5.6 5.9 5.6

3.8

4.0

3.9

2.7

3.5

3.9

3.7

6.0

6.3

5.9

6.2

6.9

6.1

6.6

5.9

4.8

4.0

4.5

4.1

3.4

3.9

4.6

4.8

4.0

4.2

3.6

4.0

4.6

4.0

4.1

3.9

3.8

4.2

4.5

4.2

3.4

4.2

3.9

3.6

2.7

3.8

3.6

3.4

2.4

3.0

2.8

3.9

3.7

3.8

4.1

4.3

3.7

3.8

4.1

4.5

4.3

5.0

3.9

4.1

4.3

4.2

4.9

4.4

4.0

4.4

3.7

4.5

3.6

4.6

2.5

3.1

3.3

2.6

3.3

2.7

2.9

3.8

3.6

3.2

3.6

3.3

3.8

3.4

3.5

4.4

4.8

4.9

4.4

4.1

4.0

4.5

4.6

4.7

4.9

4.5

4.1

4.4

4.5

4.4

5.0

respectively). The entrepreneurs working for Other Customers were most likely to believe this statement (6.9). The differences were statistically significant between »Metsäliitto« and Other Customers and between »Stora Enso« and Other Customers. The entrepreneurs who reported »Stora Enso« as their most important customer were most likely (6.0) to believe that they understood what regional entrepreneur-

T. Palander et al. Potential Mechanisms for Co-operation between Transportation Entrepreneurs and Customers ... (89–103)

Table 2 Entrepreneurs’ interest in and perceived feasibility of various forms of co-operation. 1 = Fully disagree; 2 = Disagree; 3 = Mildly disagree; 4 = Don’t know; 5 = Mildly agree; 6 = Agree; 7 = Fully agree Tablica 2. Interesi poduzetnika i percipirana izvedivost razli~itih oblika suradnje. 1 = Uop}e se ne slaèm; 2 = Ne slaèm se; 3 = Blago se ne slaèm; 4 = Ne znam; 5 = Blago se slaèm; 6 = Slaèm se; 7 = Potpuno se slaèm Form of co-operation – Oblik suradnje Sub-contracting – Podugovaranje Joint venture – Zajedni~ki pothvat/ulaganje Joint venture for sales and marketing – Zajedni~ki pothvat/ulaganje za prodaju i marketing Merger – Spajanje Company acquisition – Kupnja poduze}a ship means, whereas the entrepreneurs who worked for the Finnish »Forest and Park Service« were least likely (5.0) to share that belief. The difference between the two groups was statistically significant. Most entrepreneurs were not interested in expanding their company into a regional entrepreneurship (mean Likert score of 3.1). The entrepreneurs working for »UPM« were most interested (3.8) in expanding their company, whereas the entrepreneurs working for Other Customers were least interested (2.4). This difference was statistically significant. The entrepreneurs who had large companies were slightly more interested in expanding their company (3.9) than the entrepreneurs of small (3.0) and medium (2.8) companies, but the differences were not significant. The entrepreneurs who owned four or five trucks believed more often than any other group (small, medium, large) that the growth of their company would increase profitability (3.6), but at the same time, they were more reluctant (3.3) than entrepreneurs of other large companies to expand their company size. The entrepreneurs with four or five trucks regarded regional entrepreneurship more positively (5.1) than any other group. The entrepreneurs responded negatively (a mean Likert value of 3.0) to the statement that they had enough ability to found a joint venture capable of taking care of both harvesting and transporting wood. The entrepreneurs who owned four or five trucks were the group that was most interested in co-operation with harvesting entrepreneurs (4.2). The entrepreneurs with large companies were more positive (3.8) about this statement than the entrepreneurs with small companies (2.7), and the difference was statistically significant. This was also true for the belief that their company had enough resources to acquire planning and data management systems; the entrepreneurs with large companies agreed with this statement (4.4) significantly more than entrepreneurs with small companies (3.4). Entrepreneurs with small companies were significantly more posi-

Mean Likert value – Srednja Likertova vrijednost Interest – Interes Feasibility – Izvedivost 3.5 3.8 4.1 4.0 4.7 4.5 3.7 3.7 4.0 4.3

tive (4.5) that they had enough ability to use additional information technology than the entrepreneurs with medium companies (3.6). The entrepreneurs with large companies and the entrepreneurs with four or five trucks were even more convinced (4.6 and 4.9, respectively) of their ability. The entrepreneurs with small companies were least likely (3.9) and those with a large company were most likely (4.8) to believe that the bargaining position of a regional entrepreneur would be stronger than under a normal salary-based contract. This difference was statistically significant. The entrepreneurs who worked for Other Customers believed significantly less than the entrepreneurs who worked for »Stora Enso« (3.4 and 4.8, respectively) that regional entrepreneurship would improve their bargaining position. We investigated the interest of entrepreneurs in various potential forms of co-operation and the perceived feasibility of that form, with the results pooled for all respondents (Table 2). Then we repeated this analysis firstly for entrepreneurs grouped based on their biggest customer (Fig. 3). The mean Likert values ranged from 2.8 (not very interesting or feasible) to 5.3 (quite interesting and feasible). The entrepreneurs who worked for »Metsäliitto« were less interested in a joint venture for sales and marketing of services (3.9) than other entrepreneurs. The differences were significant between »Metsäliitto« and »Stora Enso« (5.2) and between »Metsäliitto« and Other Customers (5.3). The entrepreneurs who worked for »UPM« evaluated company acquisition as less feasible (3.8) than other entrepreneurs. The differences were statistically significant between »UPM« and the Finnish »Forest and Park Service« (5.3) and between »UPM« and »Metsäliitto« (4.9). Entrepreneurs who worked for »UPM« also considered merger to be less feasible (3.1) than other entrepreneurs, and the difference between »UPM« and the Finnish »Forest and Park Service« (4.4) was statistically significant. There was a significant correlation in the interest towards merger and company acquisition (t = Croat. j. for. eng. 33(2012)1

Potential Mechanisms for Co-operation between Transportation Entrepreneurs and Customers ... (89â&#x20AC;&#x201C;103) T. Palander et al.

Fig. 3 Attitudes of entrepreneurs towards various forms of consortium. Entrepreneurs were divided into groups based on their most important customer (I = interesting; F = feasible). 1 = Not at all interesting/feasible; 2 = Not interesting/feasible; 3 = Not very interesting/feasible; 4 = Donâ&#x20AC;&#x2122;t know; 5 = Quite interesting/feasible; 6 = Interesting/feasible; 7 = Very interesting/feasible Slika 3. Stavovi poduzetnika prema razli~itim oblicima udru`ivanja. Poduzetnici su podijeljeni u grupe prema najva`nijim korisnicima (I = interesantno; F = izvedivo). 1 = Uop}e nije interesantno/izvedivo; 2 = Nije interesantno/izvedivo; 3 = Nije jako interesantno/izvedivo; 4 = Ne znam; 5 = Prili~no interesantno/izvedivo; 6 = Interesantno/izvedivo; 7 = Jako interesantno/izvedivo

Fig. 4 Attitudes of transportation entrepreneurs with different company sizes towards various forms of consortium (I = interesting; F = feasible). 1 = Not at all interesting/feasible; 2 = Not interesting/feasible; 3 = Not very interesting/feasible; 4 = Donâ&#x20AC;&#x2122;t know; 5 = Quite interesting/feasible; 6 = Interesting/ feasible; 7 = Very interesting/feasible Slika 4. Stavovi poduzetnika u prijevozu drva s razli~itom veli~inom poduze}a prema odre|enim oblicima udru`ivanja (I = interesantno; F = izvedivo). 1 = Uop}e nije interesantno/izvedivo; 2 = Nije interesantno/izvedivo; 3 = Nije jako interesantno/izvedivo; 4 = Ne znam; 5 = Prili~no interesantno/izvedivo; 6 = Interesantno/izvedivo; 7 = Jako interesantno/izvedivo 0.433) and in the feasibility of these alternatives (t = 0.402). We performed the same analysis, but this time based on company size (Fig. 4). All company sizes ranked a joint venture for sales and marketing as the most interesting alternative. Small companies also Croat. j. for. eng. 33(2012)1

considered this option to be the most feasible, but large companies ranked it in third place in terms of feasibility, with subcontracting and company acquisition ranked higher. Medium companies thought that joint venture and joint venture for sales and marketing were the most feasible alternatives. Small

T. Palander et al. Potential Mechanisms for Co-operation between Transportation Entrepreneurs and Customers ... (89–103)

companies were more interested in a merger (mean Likert value = 4.0) than large companies (2.8), and the difference was significant. Table 3 summarizes the underlying factors responsible for the selection of the alternatives for each group of customers. The entrepreneurs working for »Stora Enso« were significantly less interested (mean Likert value = 2.6) in expanding their company than the entrepreneurs working for »UPM« (3.9). The entrepreneurs working for »Metsäliitto« (5.0) believed that they had enough monetary resources to expand their activities significantly more than entrepreneurs working for Other Customers (3.3). Entrepreneurs working for Other Customers believed that expanding their company would require hiring of additional staff for supervision and planning duties (5.9) significantly more than those who worked for the Finnish »Forest and Park Service« (4.8). Table 3 also summarizes the responses to the same questions, but grouped by company size. Almost all respondents thought (mean Likert value = 6.2) that there will be a shortage of drivers in the near future. Some entrepreneurs noted that this was al-

ready a problem that limited expansion of their company. Respondents were most negative about their willingness to expand their company (3.1) and about whether increasing the company’s size would increase their profitability (2.6). The small and medium companies (2.5 and 2.3, respectively) rated this probability lower than large companies (3.3), and the difference was significant between the large and medium companies. The willingness to expand received a mean ranking of 2.9 for the small and medium companies, versus 3.7 for the large companies. The entrepreneurs were neutral about whether they were interested in co-operation with harvesting entrepreneurs (4.0, 3.9 and 4.6 for small, medium and large companies, respectively). However, some entrepreneurs in each size group were very interested in this option. Respondents with medium companies believed that expanding their company would require hiring additional staff for monitoring and planning duties more (5.9) than those with small or large company (5.1), and the difference was statistically significant between the small and medium companies. Those with small and medium companies were less positive that better routing and backhaul planning

Table 3 Levels of agreement with statements that explained the choice of a form of consortium. 1 = Fully disagree; 2 = Disagree; 3 = Mildly disagree; 4 = Don’t know; 5 = Mildly agree; 6 = Agree; 7 = Fully agree. Entrepreneurs were divided into groups based on their company size (Small (1 truck) = S; Medium (2 trucks) = M; Large (3 or more trucks) = L) and their most important customer (»Stora Enso« = A; »UPM« = B; »Metsäliitto« = C; »Forest and Park Service« = D; Other Customers = E) Tablica 3. Razina slaganja s tvrdnjama koje obja{njavaju izbor oblika konzorcija. 1 = Uop}e se ne slaèm; 2 = Ne slaèm se; 3 = Blago se ne slaèm; 4 = Ne znam; 5 = Blago se slaèm; 6 = Slaèm se; 7 = Potpuno se slaèm. Poduzetnici su podijeljeni u grupe prema veli~ini tvrtke (Mali /1 kamion/ = S; Srednji /2 kamiona/ = M; Veliki /3 ili vi{e kamiona/ = L) i najva`nijim korisnicima (»Stora Enso« = A; »UPM« = B; »Metsäliitto« = C; »[umska i park slu`ba« = D; Ostali korisnici = E) Customer – Korisnik I have considered selling my company to someone who is expanding their activities Razmatrao sam prodaju svoje tvrtke nekomu tko pro{iruje aktivnosti I am willing to expand my company – Voljan sam pove}ati svoje poduze}e I have enough monetary resources to expand my activities (savings or ability to obtain a loan) Imam dovoljno nov~anih resursa da pro{irim svoje aktivnosti (u{te|evina ili mogu}nost dobivanja zajma) There will be a shortage of drivers in the future – U budu}nosti }e nedostajati voza~a I am interested in co-operation with harvesting entrepreneurs Zainteresiran sam za suradnju s poduzetnicima na pridobivanju drva An increase in the size of the company will also increase its profitability Pove}anje veli~ine poduze}a tako|er }e pove}ati njegovu profitabilnost Expanding my company will require the hiring of additional staff for supervision and planning duties Pro{irenje }e poduze}a zahtijevati unajmljivanje dodatnoga osoblja za poslove nadzora i planiranja Improving efficiency will let me hire additional staff Pobolj{anje }e mi u~inkovitosti omogu}iti unajmljivanje dodatnoga osoblja Better routing and backhaul planning will save money Bolje odre|ivanje ruta i planiranje prijevoza u{tedjet }e novac

Company size Veli~ina tvrtke S M L

3.3

3.8

4.2

2.9

3.6

3.4

4.6

2.8

2.6

3.9

3.0

2.9

2.7

2.9

3.7

4.5

4.3

5.0

3.3

4.4

3.8

4.8

6.0

6.5

6.4

6.5

6.3

6.2

6.3

6.1

4.6

3.8

5.0

4.3

4.1

4.0

3.9

4.6

2.8

2.4

3.2

2.1

2.6

2.5

2.3

3.3

5.5

5.1

4.8

5.9

5.1

5.9

5.1

4.0

3.8

4.3

3.4

4.3

3.8

4.2

4.1

5.1

4.9

5.1

4.6

4.7

4.4

5.3

5.4

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would reduce their costs (4.4 and 5.3, respectively) than entrepreneurs with large companies (5.5), and the difference between the small and large companies was significant. The entrepreneurs with medium companies had thought about selling their company more often (4.6) than other entrepreneurs (3.4 for small company and 2.8 for large companies), and the difference between the medium and large companies was significant.

4. Discussion – Rasprava Concerning the main objective of investigation – how to develop co-operation between the transportation entrepreneurs and to facilitate outsourcing in forest industry, the important aims were to learn what factors are preventing regional entrepreneurship from becoming more common. It seemed that nothing happened since 2005 that could be interpreted as increase of outsourcing (Fig. 1). Therefore, this study is timely and relevant. An important obstacle was the lack of information about the plans of the entrepreneur’s most important customer with respect to regional entrepreneurship. Some entrepreneurs believed that their customer had kept them poorly informed about the company’s plans, and that the customer’s attitude towards regional entrepreneurship was unclear. In this context, it is important to remember that regional entrepreneurship is a form of extended entrepreneurship (i.e., increased transportation responsibilities) that is often part of a company’s outsourcing strategy. Despite the bad reputation of outsourcing, general attitudes towards this strategy can still be positive if entrepreneurs understand the situation and are confident that their customers will support them through the transition to the regional entrepreneurship. Transportation entrepreneurs had similar views about many statements regarding regional entrepreneurship. Most perceived that regional entrepreneurship was only a way to transfer the customer’s planning duties, management responsibilities, and costs to entrepreneurs without providing adequate compensation. This view is a major, previously unremarked obstacle to the development of regional entrepreneurship because even entrepreneurs whose customers were promoting regional entrepreneurship believed that the goal was to shift these burdens to the entrepreneur. It also seems that wood-procurement organizations that have begun applying regional entrepreneurship are working similarly to how they used to work before adopting this approach; for example, they still define how entrepreneurs should manage their operations instead of leaving the choice to the entrepreneur. Most entreCroat. j. for. eng. 33(2012)1

preneurs who responded to our survey wanted to manage their routing and inventory control planning as well as negotiating pay rates from a position of more power by forming a bigger consortium. Although materials-related functions related to the flow of wood have been developed by forest industry, our results suggest that the monetary chains and the information chains must be developed further because of their importance to an entrepreneur’s business operations. According to Beimborn et al. (2005) the monetary chain is rarely designed and optimized to provide a competitive advantage on its own because it is usually a secondary process to support a material chain. Another obstacle to the development of regional entrepreneurship involves the difficulty of co-operation between entrepreneurs. Our results suggest that it will be necessary to develop an operational environment in which business networks are in place that let entrepreneurs simultaneously compete and cooperate in dynamic entrepreneurial environment. These aspects of co-operation have been important targets of research, where operating models have been developed to meet the management needs imposed by networking (Bengtsson and Kock 2000; Bititci et al. 2005; Bertolini and Giovannetti 2006; Jack et al. 2008). However, this approach remains unknown in the regional entrepreneurship of wood transportation sector although customers are operating successfully. Regional entrepreneurship was not expected to improve the bargaining position of wood suppliers. In the current economic situation, with increasing global competition, this form of entrepreneurship was seen as a possible way to survive, although the entrepreneurs were generally more interested in the pay-rate policies of their customers than in regional entrepreneurship. Almost all entrepreneurs mentioned an imbalance between pay rates and transportation costs as a serious obstacle to the development of regional entrepreneurship. In addition, many respondents described their current economic situation as unsustainable. This is quite understandable given that our study was conducted in 2006, when the profitability of the Finnish forestry sector was poor because of rapidly rising fuel prices and a strike that affected many paper mills. In addition, the recession and a delay in the education of truck drivers also reduced profits. We found that entrepreneurs with four or five trucks were most content with their situation, and this group regarded regional entrepreneurship more positively than any other group. Although differences between this company group and other large companies were not statistically significant, this

T. Palander et al. Potential Mechanisms for Co-operation between Transportation Entrepreneurs and Customers ... (89–103)

group believed more in their skills and opportunities. Entrepreneurs who owned four or five trucks also believed more often than any other group that the growth of their company would increase profitability, but at the same time, they were more reluctant to expand their company size than entrepreneurs of other large companies. These results appear to be contradictory, but the results can be explained by the results of Soirinsuo and Mäkinen (2009), who calculated that the most profitable company size in Finland was five or six trucks, after which the growth of the company did not seem to improve profitability. It is possible that entrepreneurs with four or five trucks saw that growth had been profitable up to their current company size, but feared that future growth would require investments that were bigger than the expected revenues. In theory they would rearrange transportation functions if the costs of internal transactions were less than the value of what is gained by networking as suggested by Coase (1992). On the other hand, it follows that if entrepreneurs can lower internal transaction costs, there will be more rearrangements, and the wood procurement network will become more productive. Companies with two trucks seemed to be a problematic size. These entrepreneurs were least interested in expanding their company and least likely to believe that growth of the company would improve their profitability. These entrepreneurs believed most commonly that the forest industry was only promoting regional entrepreneurship as a way to transfer wood-procurement costs to the transportation entrepreneurs and that it would become necessary to hire additional staff for management of their operations. Owners of these companies had also more often considered selling their company than other entrepreneurs, and they had more doubts about their abilities and as to whether their resources were sufficient to permit growth. It seems that two trucks are insufficient to provide economies of scale, and that to grow, these entrepreneurs would have had to change their operation models by hiring additional staff. However, this change increases internal transaction costs of the transportation company (Fig. 2). Later it may also increase external transaction costs of wood procurement company, which may be considered as a conflict of outsourcing (Williamson 1975, 1985; Coase 1991). For wood procurement network, it appears to be more difficult to achieve good profitability simply by increasing the workload of the entrepreneur, as can be done in one-truck family enterprises. This became evident from the total volume of wood carried by the transportation entrepreneurs, because the productivity (m3/h) per vehicle of two-truck compa-

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nies seemed to be lower than that of one-truck family enterprises. Regional entrepreneurship has been applied in wood harvesting of wood procurement network during the last decade. We found that the transportation entrepreneurs were interested in co-operation with wood harvesting entrepreneurs. These were entrepreneurs with large transportation companies. However, most entrepreneurs felt they lacked the skills they would require to manage a company that would take care of both wood harvesting and transportation. This problem could be solved by forming a consortium that combined the talents of an entrepreneur with harvesting skills with the talents of one with transportation skills. Otherwise, wood suppliers’ role could even be given to harvesting entrepreneurs who would be responsible for large areas of wood procurement. In this entrepreneurial environment transportation entrepreneurs could operate as sub-contractors of harvesting entrepreneurs as suggested in Fig. 2. We also wanted to learn how interested entrepreneurs would be in forming various kinds of consortia and their perceptions of how feasible these alternatives would be. The alternatives that we proposed were not especially interesting or perceived as easily feasible to the entrepreneurs, though opinions varied. The best alternative appeared to be a joint venture for sales and marketing of services. This joint venture would sign contracts with customers, and then each shareholder would sign their own contract with the joint venture. All monetary transactions would be based on invoicing for services rather than on salaries. This was the only alternative that was not opposed by any group of transportation entrepreneurs. The result indicated that invoicing encapsulated in the financial chain should be addressed in outsourcing as an autonomous source of competitive advantage, as suggested by Beimborn et al. (2005). There was also a statistically significant correlation between interest towards mergers and interest towards company acquisitions. On the other hand, there was a significant correlation between the interest in and perceived feasibility of the various consortium alternatives. This is obvious, because when entrepreneurs were interested in some form of consortium, they also saw it as a feasible alternative or at least as more feasible than other alternatives in the current working environment. It is good to note that this survey established the current performance status (»gap«) being provided based on the operational-level entrepreneurs’ opinions. In future, this strategic analysis could be continued using the collected benchmarks of SKAL. It is noteworthy that two groups of entrepreneurs were more interested in forming a joint venture reCroat. j. for. eng. 33(2012)1

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sponsible for sales and marketing of their services than was the case for two other groups of entrepreneurs. One group of entrepreneurs was more interested in a company acquisition and also believed more strongly than other entrepreneurs that they had the financial resources to expand their company. One reason for the lack of interest in forming consortia was the long work week. On average, an entrepreneur worked almost 70 hours per week, and in some cases, more than 100 hours. Clearly, the work week is too long for the well-being of entrepreneurs, and this may explain why most entrepreneurs were not interested in expanding their company: they feared the possibility of further increases in their work week. On the other hand, subcontracting was not an interesting alternative either for the small and medium companies, so it is understandable that selling the company was a more interesting alternative for these entrepreneurs. In the future, more research will be needed to develop an operational environment in which increasing company size is an attractive option. Opinions about co-operation reflected the views of entrepreneurs who had not yet adopted regional entrepreneurship. These entrepreneurs are the group with the most potential for the development of improved co-operation between wood suppliers and their customers. These entrepreneurs are described as institutions or transportation companies in the transaction model (Fig. 2). The results indicated that only the first steps have been taken towards outsourcing, because practical details about the forms of consortia are still unclear. This was also revealed by comparing the present results with those of theoretical studies of co-operation and its objectives by Högnäs (2000). For example, transportation entrepreneurs whose biggest customer was »Metsäliitto« and those whose biggest customer was »UPM« had different conceptions of the effects of regional entrepreneurship on cost effectiveness of the wood-procurement network and on the profitability of the transportation operation. As they understood co-operation differently, it will be necessary to propose consistent developmental decisions to ensure that both groups of entrepreneurs have the same understanding. A joint venture that focuses on sales and marketing could be a way to promote the development of outsourcing by awarding larger contracts than are currently awarded and larger transportation functions thereby giving entrepreneurs an incentive to increase their operational capacity and giving entrepreneurs more freedom of action. Before drawing further conclusions about this possibility, more studies will be necessary to confirm, for example, whether this form of organization can be developed and Croat. j. for. eng. 33(2012)1

understood by entrepreneurs, and how the coordinator of such an organization would manage the chains of materials, money, and information required to support transactions of the transportation function (Palander et al. 2006).

5. Conclusions – Zaklju~ci The results of the present study suggest that external reorganization of the truck transportation sector and internal structural changes in transportation entrepreneurship are currently underway, but that the objectives of these changes are unclear for all stakeholders in the wood-procurement network. To facilitate the development of co-operation in the wood transportation, the objectives of co-operation should be determined quickly and communicated to all stakeholders. The challenge for transportation entrepreneurs is to find the best set of interconnected service solutions that meet the strategic needs of wood procurement network. Those who are considering outsourcing of the transportation function must be aware of the linkage between reducing the staff in wood-procurement organizations and reorganizing the wood transportation sector, and the effect of the resulting operating environment on opportunities for co-operation. For better environment the entrepreneurs felt that the most interesting form of consortium between suppliers, which would let them respond better to outsourcing, would be the formation of a joint venture responsible for sales and marketing of their services. Such a company would develop an overall contract with each customer, and then each shareholder in the joint venture would sign their own contracts with the venture to share the work. All transactions would be based on invoicing instead of the current salary-based approach. However, entrepreneurs did not believe that their profitability would increase by expanding their company size in the current entrepreneurial environment. To conclude, if the aim of co-operation is to outsource the wood transportation function, decision-makers in the Finnish forest industry should modify the current environment so that larger, more organized consortia of wood suppliers would become more profitable than they presently are.

Acknowledgement – Zahvala Authors are grateful to »Metsämiesten Säätiö« for funding. We also thank all the entrepreneurs who participated in our study, and Kari Palojärvi, Director of the Timber Carriers Association, for making this study possible.

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6. References – Literatura Ala-Fossi, A., Sikanen, L., Asikainen, A., 2004: Forest contractor’s attitude and readiness for area responsible contracting. NSR Conference on Forest Operations, Finland, 30 – 31 August. Silva Carelica 45: 238–244. Ansoff, I. 1965: Corporate Strategy. McGraw Hill, New York. Beimborn, D., Franke, J., Weitzel, T., 2005: The Role of Experience for Outsourcing Evaluation. Wirtschaftsinformatik 47(6): 431–440. Bengtsson, M., Kock, S., 2000: »Coopetition« in business networks – to cooperate and compete simultaneously. Industrial Marketing Management 29(5): 411–426. Bertolini, P., Giovannetti, E., 2006: Industrial districts and internationalization: the case of the agri-food industry in Modena, Italy. Entrepreneurship and regional development 18(4): 279–304. Bititci, U. S., Mendibil, K., Martinez, V., Albores, P., 2005: Measuring and managing performance in extended enterprises. International Journal of Operations and Production Management 25(4): 333–353. Coase, R., 1991: Contracts and the Activities of Firms. Journal of Law and Economics 34: 451–452. Coase, R., 1992: The Institutional Structure of Production: The 1991 Alfred Nobel Memorial Prize Lecture in Economic Sciences (Les Prix Nobel). American Economic Review 82(4): 713–719. Coase, R., 1998: The New Institutional Economics. American Economic Review 88(2), p. 72-74. Demsetz, H., 2003: Ownership and the Externality Problem. In Property Rights: Co-operation, Conflict, and Law, ed. T. L. Anderson and F. S. McChesney, Princeton, N. J.: Princeton University Press.

Högnäs, T., 2000: Kohti kumppanuutta metsäalan konetyöja kuljetusurakoinnissa. (Towards companionship in harvest and transport contracting). PhD diss., University of Helsinki. Metsähallituksen metsätalouden julkaisuja 28, 134 p. (In Finnish.) Jack S., Dodd, S. D., Anderson, A. R., 2008: Change and the development of entrepreneurial networks over time: a processual perspective. Entrepreneurship and regional development 20(2): 125–159. Palander, T., Säynäjoki, T., Högnäs, T., 2006: Puutavaran autokuljetuksen uudet organisointimallit. [New organizing models of timber truck transportation]. Metsätieteen aikakauskirja 1: 5–22. (In Finnish) Palander, T., Väätäinen, J., 2005: Impacts of inter-enterprise collaboration and backhauling on wood procurement in Finland. Scandinavian Journal of Forest Research 20(2): 177–183. Soirinsuo, J., Mäkinen, P., 2009: Growth and economies of scale among timber haulage companies. The 54th Annual International Council for Small Business: The Dynamism of Small Business: Theory, Practice and Policy, June 21–24, Seoul, Korea. SPSS Inc 1988: SPSS-X User’s Guide. 3rd ed. SPSS Inc., Chicago. Williamson, O.E., 1975: Markets and hierarchies. Analysis and antitrust implications. The Free Press. New York. Williamson, O.E., 1981: The Economics of Organization: The Transaction Cost Approach. The American Journal of Sociology 87(3): 548–577. Williamson, O.E., 1985: The economic institutions of capitalism. Firms, markets, relational contracting. The Free Press. New York.

Sa`etak

Mogu}i mehanizmi suradnje poduzetnika i korisnika prijevoza drva: studij slu~aja regionalnoga poduzetni{tva u Finskoj Gotovo sve drvo kori{teno u finskoj {umskoj industriji u nekoj se fazi, unutar mreè dobavljanja drva od {ume do pilana i tvornica, transportira kamionima. Trenuta~no otprilike 850 finskih tvrtki za transport drva posjeduje oko 1700 kamiona i zapo{ljava oko 2600 voza~a. Tri su ~etvrtine od tih poduzetni~kih tvrtki za prijevoz drva mala poduze}a; obitelji posjeduju jedan ili dva kamiona, koji obi~no vi{e od 90 % drva dostavljaju samo jednomu korisniku. Danas, u podru~ju dobavljanja drva, s ukupnim udjelom od 90 % drva koje se transportira u Finskoj, prevladavaju tri najve}a korisnika (»Stora Enso«, »UPM«, i »Metsäliitto«). Tradicionalno takve organizacije za dobavljanje drva potpisuju izravne ugovore o prijevozu sa svakom od tvrtki za transport drva. Takvi su ugovori kori{teni da se strogo definiraju prijevozni~ki poslovi za koje su poduzetnici odgovorni. Uobi~ajeno, ve}ina je tih ugovora bila sklopljena sa zaposlenicima organizacija za dobavljanje drva i odre|ivala je fiksnu pla}u za voza~a kamiona. Nedavno je {umska industrija u nastojanjima da smanji svoje operativne tro{kove zapo~ela s poku{ajima da mnoge djelatnosti, uklju~uju}i i prijevoz drva, izdvoji iz svoga poslovanja. Ipak, taj je prijelaz samo djelomi~no ostvaren, te sada{nji oblik poduzetni{tva u prijevozu drva jo{ uvijek zadràva mnoga obilje`ja tradicionalnoga sustava u transportu drva. U provedenom se istraìvanju poduzetnici na prijevozu drva smatraju isporu~iteljima drva, a organizacije za dobavljanje drva u {umskoj industriji predstavljaju njihove korisnike, odnosno korisnike usluga transporta drva.

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U ovom promjenjivom poslovnom okruènju {umska industrija nastoji unaprijediti vlastitu tro{kovnu u~inkovitost tako da privatnim prijevoznicima drva nudi sporazume o pro{irenom poduzetni{tvu kojima se pove}avaju njihove odgovornosti. Zapravo, pro{ireno je poduzetni{tvo prva faza u zapo~etom procesu prijelaza od ugovornoga modela u mreì dobavljanja drva ka modelu izdvajanja transporta u mreì isporu~ivanja drva. Za finsku {umsku industriju takvo je pro{ireno poduzetni{tvo logi~na posljedica izdvajanja poslovnih funkcija koje nisu vezane uz temeljnu djelatnost poduze}a (outsourcing), postupak koji na me|unarodnim trì{tima postaje sve vi{e uobi~ajen. Na temelju teorije o poslovnim tro{kovima izdvajanje prijevoza drva mogli bi se smanjiti ukupni tro{kovi dobavljanja sirovoga materijala do tvornice. Ako je ta teorija to~na, unaprijedila bi se ukupna tro{kovna u~inkovitost i me|unarodna konkurentnost {umske industrije. Regionalno je poduzetni{tvo jedan od oblika pro{irenoga poduzetni{tva u kojem se naglasak stavlja na suradnju isporu~itelja drva (poduzetnika) i korisnika prijevoza drva. U sektoru transporta drva regionalno je poduzetni{tvo relativna novost, iako su poduzetnici na prijevozu zemlje i gradnji cesta primjenjivali takav pristup ve} desetlje}ima. U primjeni tipi~noga regionalnoga poduzetni{tva organizacije za dobavljanje drva potpisale bi ugovore o prijevozu s manjim brojem poduzetnika, od kojih je svaki odgovoran za ve}e podru~je (regiju). Takvi bi pro{ireni ugovori uklju~ivali prijevozni~ke zadatke koji su ve}i i raznolikiji, u {to je uklju~eno i vi{e odgovornosti nego u klasi~nim ugovorima. Regionalni poduzetnik moè ispuniti svoje ugovorne obveze rade}i sam ili u suradnji s drugim poduzetnicima. Navedeni se oblik suradnje moè ostvariti kroz razli~ite na~ine udruìvanja: podugovaranjem poslova, zajedni~kim poslovnim pothvatima i ulaganjima, spajanjem poduze}a, kupnjom poduze}a. Regionalno poduzetni{tvo korisnici prijevoza drva sporo prihva}aju. Me|utim, dok odre|eni korisnici tek po~inju istraìvati ugovore s pro{irenim poduzetni{tvom, pojedini su korisnici s poduzetnicima ve} potpisali takve ugovore. Ispitivanja pokazuju da se promicanje regionalnoga poduzetni{tva i izdvajanje prijevoza moè posti}i pove}anjem veli~ine ugovora, pro{iruju}i broj zadataka i odgovornosti uklju~enih u ugovor, te davanjem poduzetnicima vi{e slobode u njihovim aktivnostima. U transportu drva takvi postupci zahtijevaju suradnju poduzetnika u osnivanju konzorcija, koji potencijalno mogu biti profitabilniji. Ciljevi su provedenoga istraìvanja bili da se ispitaju na~ini na koje je mogu}e pobolj{ati suradnju u pristupu regionalnoga poduzetni{tva u transportu drva i da se olak{a zapo~eti proces izdvajanja odgovornosti u dobavljanju drva u finskoj {umskoj industriji. Ispitana je suradnja izme|u poduzetnika na prijevozu (isporu~itelji drva) te izme|u poduzetnika i {umske industrije (korisnici prijevoza). Poduzetnicima u prijevozu drva koji rade unutar mreè dobavljanja drva korisnika poslan je upitnik. Poduzetnici smatraju da najzanimljiviji oblik konzorcija prijevoznika drva, koji im moè omogu}iti bolji odgovor na regionalno poduzetni{tvo i vanjsko ugovaranje prijevoza (outsourcing), predstavlja formiranje zajedni~kih pothvata i ulaganja u prodaji i marketingu njihovih usluga. Takva bi tvrtka razvila sveobuhvatni ugovor sa svakim korisnikom, zatim bi svaki sudionik u takvu ulaganju/pothvatu potpisao vlastiti ugovor sa zajedni~kom tvrtkom radi raspodjele poslova. Sve bi se transakcije temeljile na fakturiranju umjesto sada{njega pristupa na osnovi pla}a. Ipak, poduzetnici ne vjeruju da }e se u postoje}em poduzetni~kom okruènju pro{irenjem njihovih odgovornosti pove}ati njihova profitabilnost. Ako je cilj suradnje izdvajanje transporta drva, donositelji odluka u finskoj {umskoj industriji trebaju promijeniti sada{nje okruènje tako da ve}i i organiziraniji konzorciji poduzetnika koji prevoze drvo postanu profitabilniji nego {to to trenuta~no jesu u pristupu regionalnoga poduzetni{tva. Klju~ne rije~i: dobavljanje drva, outsourcing, regionalno poduzetni{tvo, umreàvanje i povezivanje

Authors’ address – Adresa autorâ:

Received (Primljeno): July 17, 2011 Accepted (Prihva}eno): November 21, 2011 Croat. j. for. eng. 33(2012)1

Prof. Teijo Palander, PhD. e-mail: teijo.s.palander@uef.fi Mika Vainikka, MSc. e-mail: mika.vainikka@uef.fi Antti Yletyinen, BSc. e-mail: antti.yletyinen@student.uef.fi University of Eastern Finland Faculty of Science and Forestry Joensuu Campus Yliopistokatu 2 P.O. Box 111 FI-80101 Joensuu FINLAND

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Original scientific paper – Izvorni znanstveni rad

The Present State and Prospects of Slovenian Private Forest Owners’ Cooperation within Machinery Rings [pela Pezdev{ek Malovrh, Petra Gro{elj, Lidija Zadnik Stirn, Janez Kr~ Abstract – Nacrtak The study analyzes the challenges and prospects of private forest owners’ cooperation based on the use of machinery in Slovenia applying the strengths, weaknesses, opportunities and threats approach (SWOT analysis) in combination with the analytic hierarchy process (AHP). The data from questionnaires with forest owners and presidents of machinery rings were used to develop and to analyze the strategies for forest owners’ cooperation. The results reveal that the members of machinery rings are only partly satisfied with the operation of the existing rings and that the activities of rings meet the members’ interests related to forest management. Thus, machinery rings are recognized as a suitable form of forest owners’ cooperation. The presidents of machinery rings perceive the integration of farmers and private forest owners, as well as knowing the level of mechanization of members as major strengths of machinery rings. Further, strengthening the operation of machinery rings in the field of forestry is recognized as an important opportunity. The shortage of means for operation is identified as a weakness for machinery rings, and the lack of subsidies for investments in equipment is identified as a critical threat. However, the rank of importance of the SWOT groups leads to defensive approach in the strategic planning where machinery rings have to minimize weaknesses in order to avoid threats. These results provide important insights in the future development of forest owners’ cooperation based on common use of machinery. Keywords: cooperation based on the use of machinery, machinery rings, private forests, survey, A’WOT method, strategic planning

1. Introduction – Uvod Renewable natural resources, wood being among the most important ones, are limited and their availability depends on terrain and climate circumstances/conditions, on the technological development and its application in forest management. Slovenia maintains close-to-nature forestry, which incorporates two main principles: sustainability of all forest functions and imitation of natural processes (Sustainable Forest Management). This principle demands for a significant incorporation of the social component into forest management activities. In Slovenia small-scale private forests are dominant as 73% of forests are privately owned (Report of the Slovenian Forest Service 2010). The property structure of Slovenian privately-owned forests reveals that 58.4% of owners have a forest property smaller Croat. j. for. eng. 33(2012)1

than 1 ha and that the average property size of private forests is less than 3 ha (Pezdev{ek Malovrh et al. 2010). The development of small-scale private forestry and management activities are strongly connected to socio-economic structural changes of the population, which are related to an increasing number of owners and to the diminishing in size of forest properties as well as a decrease of rural population (Pezdev{ek Malovrh 2006, Stampfer et al. 2001). These changes result in the absence or insufficient forest management, inefficient equipment and inadequate qualification for work, as well as in low profitability (Lahdensaari 2001). The consequences of such management practices are reflected in the lack of exploitation of natural resources as only two thirds of the potential timber removal in Slovenian private forests is implemented

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The Present State and Prospects of Slovenian Private Forest Owners’ Cooperation ... (105–114)

and according to forest management plans, less than half of silvicultural work is carried out (Report of the Slovenian Forest Service 2010). According to Stampfer et al. (2001) insufficient use of machinery and improvement of harvesting system were recognized as significant management problems in small-scale forests in Austria. The situation in Slovenia is quite similar, and in some respects the private forest management reveals additional and extended problems. Slovenia is faced with the problem of overcapacity of mechanization in agriculture and forestry. Based on the number of tractors per capita, Slovenia is in the leading position worldwide (followed by Ireland in the second place and Austria in the third place). Consequently, compared to Austria, Slovenia also deals with management problems, where the modernization of equipment, an adequate procurement of technical means (machinery), a rational investment and expansion of fully-mechanized machines are of key importance for management improvement. Modern forestry mechanization offers the benefits such as multiplying operator productivity (Spinelli and Magagnotti 2010) and enhancing work safety (Bell 2002), but on the other hand requires a significant capital investment, which often exceeds the capacity of small-scale private forest owners (Spinelli and Magagnotti 2011). So, on the one hand, technological progress depends upon the conditions and trends in individual households and, on the other hand, on financial incentives (Robek et al. 2005). In order to ensure the exploitation of machinery capacity, cooperation between owners has to be developed based on the use of machinery. The use of modern technology in small-scale forestry is only possible by cost rationalization in mechanization. Therefore, it is necessary for private forest owners to cooperate based on the use of machinery in order to increase their competitiveness. In the first phase, the aim of this paper is to establish the present state of cooperation, using a survey, based on the use of machinery in Slovenia, and in the second phase to find a hinge between the existing situation and future strategies of forest owner cooperation regarding the machinery in Slovenia by the use of A’WOT method.

2. Cooperation of forest owners regarding the use of machinery in Slovenia – Suradnja {umovlasnika u upotrebi mehanizacije u Sloveniji The existing forest owners cooperation based on the use of machinery in Slovenia, such as machinery

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rings and machinery communities, is essential to give small-scale private forest owners the chance to overcome the cost inefficient forest management and use the advantages of modern technologies. »Machinery« rings are an organized form of »neighbor assistance« and voluntary association of farmers and private forest owners in the region operating on a group basis. Cooperation based on the use of machinery is extended to the whole area of a machinery ring. Its members offer free capacity of the machinery or labor to other members through their work and use of their own machinery or lend it without an operator, but the member has to pay a price covering the machine costs. It is the responsibility of machinery rings to inform members and to provide them services. In the legal, tax and financial terms, the services are carried out directly between the client and the contractor. The first machinery rings were established in Slovenia in 1994. So far 45 machinery rings have been established. Nowadays, they practically cover the whole country. At the end of 2010 they had 6,018 members. The Societies Act (2011) forms the legal basis for machinery rings. Machinery rings are mainly engaged in agriculture; only three of them are engaged in forestry. In the previous year (2010), the members carried out on average about 140,000 hours of services, which represents approximately 23 hours of services per member (Dolen{ek 2008). The economic benefits of participation in the machinery rings are higher utilization of machines and a consequent reduction of costs, higher productivity and quality of work, as well as the possibility to generate additional income by working in other members’ farms or forests. Furthermore, the social benefits of participation in machinery rings are connected to work safety and consequently to reducing the number of accidents, to participation and offering help in labor during the holidays and peak seasons, to improved social relationship between neighbors, all resulting in improved quality of life on the farm. The main feature of machinery communities is a combined purchase of machinery and equipment. The investment is distributed among several farms, which are community members. They mostly buy machinery or equipment that is used only a few days per year or has a high capacity and high costs (Plej 2001). Most machinery communities are formed based on a verbal agreement between neighbors that are farmers or/and forest owners to purchase machinery or equipment and each member pays a share proportional to the size of his farm or forest. On the other hand they can also sign a contract for establishing a Croat. j. for. eng. 33(2012)1

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machinery community where they define the value of the machinery, the share of each member, the order for machinery use, the possibilities for switching the order, the storage of machinery, its maintenance and maintenance costs (Zgonjanin 1987). Community machinery is used by members in a predetermined order, but for the most complex pieces of machinery, members can agree that only the most qualified member of the community can operate the machine. In this particular case, the members agree on the manner of compensation costs for the work done, mostly with money or their own labor (Ekart 1978, Oto 2011). A joint purchase and use of machinery have many advantages compared to individual purchase and use. It provides the opportunity to buy modern machines and reduces the possibility of buying obsolete machinery, the maintenance of which tends to be expensive ([umi 1977).

3. Methods used – Metode rada 3.1 Surveying private forest owners and data analysis – Anketiranje privatnih {umovlasnika i analiza podataka The population sample consisted of private forest owners that were members of machinery rings (n = 1471). The members were stratified into five property size classes – strata (less than 1 ha; 1 – 5 ha; 5 – 10 ha; 10 – 30 ha; more than 30 ha). Sampling was systematically conducted within each of these five strata. In total 172 members of machinery rings were selected (Table 1). Prior to the study, the questionnaire was tested on 7 forest owners. In the year 2009 face-to-face interviews were done with selected members. The overall response rate was 45.9% (n = 79). The analysis of the frequencies of non-response showed no significant difference between property size classes (c2= 4.000; p=0.406). In the survey, respondents were asked which interests they fulfill as members of machinery rings, whether they are satisfied with machinery rings, how

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the rings fulfill their expectations and if machinery rings represent a suitable cooperation form in relation to forest owners’ needs in forest management. They assessed the satisfaction and suitability on a five point Likert scale, where one means very unsatisfied/unsuitable and five very satisfied/suitable. The statistical analyses performed in this study were based on frequency distribution across ordinal variables. Firstly, descriptive statistics and frequency histograms for all variables were produced and then the mean values considered.

3.2 A’WOT method – Metoda A’WOT SWOT analysis is a strategic management tool that helps to identify internal strengths and weaknesses and external opportunities and threats for any organization, project or individual (Dyson 2004) in order to attain a systematic approach and support the decision situation (Pesonen et a. 2001). The most important internal and external factors for the organizational future are referred to as strategic factors and they are summarized within the SWOT analysis. SWOT analysis can provide a good basis for successful strategy formulation (Kurttila et al. 2000, Rauch 2007). However, one of the main limitations of SWOT analysis is that the importance of each factor in decision making cannot be measured quantitatively and therefore, it becomes difficult to assess the potential of a factor to influence strategic decision (Dwivedi et al. 2009). Kurttila et al. (2000) examined a new hybrid method (A’WOT) where they integrated the Analytic Hierarchy Process (AHP) within SWOT analysis, for improving the usability of SWOT analysis. AHP (Saaty 1980) enables to assign a relative priority to each factor through pairwise comparison, on a scale where 1 implies equal, 3 moderate, 5 strong, 7 very strong and 9 extreme. From the pairwise comparisons the relative priority weight of each factor within each SWOT groups is computed using the eigenvector method as explained below. According to Saaty (1980), information derived from the pairwise comparisons is represented in a

Table 1 Distribution of population and sample according to strata Tablica 1. Raspodjela populacije i uzorka {umovlasnika po razredima Number of cases – Broj slu~ajeva Population distribution – Raspodjela populacije Sample distribution – Raspodjela uzorka Response distribution – Raspodjela odgovora

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Less than 1 Manje od 1 469 19 1

Strata, ha – Grupe, ha 1 to 5 5 to 10 10 to 30 1 do 5 5 do 10 10 do 30 529 218 191 51 42 36 18 18 26

More than 30 Vi{e od 30 64 24 16

Total Ukupno 1471 172 79

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comparison matrix A (1), where the comparison between i th and j th element enters into the matrix as an element aij, and inverse comparisons as aij = 1/aij é1 ê1 a 12 A=ê êM ê1 êë a 1n

a 12 1 M 1 a2 n

L a 1n ù L a2 n ú ú O M ú ú L 1 ú û

(1)

For deriving priorities, the eigenvector method is used, where the priority vector w = (w1,..., wn) is obtained by solving the equation Aw = lmax w, Where: lmax is the largest eigenvalue of the matrix A. The comparison matrix A is consistent if its entries satisfy: aij ajk = aik, for all i, j, k = l,…,n. Consistency ratio (2) measures the inconsistency among the pairwise comparisons: CR =

CI RI

(2)

lmax - n is the consistency index, n is n -1 the order of matrix A and RI is the average random consistency index. Regarding the consistency, the comparison matrix A is acceptably consistent if CR < 0.1, but in the opposite case (CR > 0.1), serious inconsistencies may exist and the AHP may not yield meaningful results, so decision makers should reconsider their judgments (Saaty 1980, [por~i} et al. 2010). The final goal of a strategic planning process, of which A’WOT analysis is an early stage, is to develop and adopt a strategy (strategic objectives) resulting in a good fit between the internal and external factors and the goals of the forms of cooperation (Kangas et.al 2003). There are two possible approaches, an offensive approach and a defensive approach. The »offensive approach« represents two possible combinations to the strategic development – the first one being the use of strengths to take opportunities, and the second the taking of opportunities by overcoming the weaknesses. Furthermore, the »defensive approach« also represents two combinations – to avoid threats by using the strengths or minimizing the weaknesses (Maru{i~ 2005). Where CI =

3.2.1 Application of A’WOT method to private forest management – Primjena metode A’WOT u upravljanju privatnim {umama In a first phase, the list of machinery rings in Slovenia was prepared working in different fields, from agriculture to forestry. To identify the factors in each SWOT group, the presidents of machinery rings that

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work in the Slovenian forestry (n = 3) were interviewed. They were asked to express their opinion about the strengths, weaknesses, opportunities and threats of their activities in private forest management. Based on the factors identified in each SWOT group, a questionnaire was prepared. This questionnaire contained pairwise comparisons between all factors in a particular SWOT group. Individual judgments were aggregated into a group judgment by the geometric mean (Lai et al. 2002, Saaty 2003, Gro{elj and Zadnik Stirn 2011, [por~i~ et al. 2011). These mean values form group comparison matrices and weights (w) were obtained for each SWOT factor using eigenvector method. The factor with the highest priority score was identified in each SWOT group. A separate questionnaire containing pairwise comparisons between the factors with highest priorities score in each SWOT group was developed. This was done to estimate the overall priorities of different SWOT groups. As some individual comparison matrices were not acceptably consistent, the respondents were asked to reconsider their judgments so as to get acceptably consistent group comparison matrices derived from individual comparison matrices.

4. Results and discussion – Rezultati i rasprava 4.1 Results of questionnaires – Rezultati upitnika The members of machinery rings are only partly satisfied with the operation of the rings (average value is 3.7). The members stated that they felt slight dissatisfaction due to the inactivity of machinery rings, lack of services offered, lack of cooperation among members, difficulties in issuing accounts and poor organization in machinery rings as machinery rings do not make the list of services offered by members or the list of machinery available to the members. The results supply evidence for a need of ongoing organizational changes in machinery rings., It is, therefore, necessary that the rings start being professional in their operation as only a well-organized cooperation system is able to organize and control the whole information and machinery needs. Furthermore, in total 93.9% of private forest owners meet the interests related to forest management in machinery rings. They highlighted 12 key interests that they fulfill in machinery rings (Table 2) that are connected to wood skidding, easier and quicker completion of work, helping in harvesting, education, excursions and demonstrations, and joint Croat. j. for. eng. 33(2012)1

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Table 2 Interests the members fulfill in machinery rings Tablica 2. Interesi koje ~lanovi ispunjavaju u udru`enju za upotrebu {umske mehanizacije Interest – Interesi Help in wood skidding – Pomo} pri privla~enju drva Easier and quicker completion of work – Lak{e i br`e obavljanje poslova Help in harvesting – Pomo} pri sje~i Education – Obrazovanje Excursions and demonstrations – Izleti i prikazi Joint purchasing of equipment – Zajedni~ka nabava opreme Offering services with agricultural machinery to other members Ponuda usluga poljoprivredne mehanizacije drugim ~lanovima Getting information – Dobivanje informacija Social help – Socijalna pomo} Economic interest – Ekonomski interes Excise duties – Tro{arine Timber sale – Prodaja drva

Share, % Udio, % 13.3 13.3 12.0 10.7 9.3 9.3 6.7 6.7 4.0 2.7 2.7 2.7

purchasing of equipment. Less often they fulfill the interests that are related to timber sale, excise duties, economical interest, social help and offering services with agriculture mechanization to other members. Nevertheless, the members are unable to sufficiently meet the following interests in machinery rings: the production of wood chips, execution of silvicultural work, joint purchases of machinery, promotion of forest management intensification, forest

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products marketing and winter maintenance of forest roads. For most members, machinery rings are a suitable form of cooperation in relation to their needs in forest management (average value = 4.0). These findings relate to the fact that the cooperation based on the use of machinery will also be important in the future, especially having in mind the socio-economic changes from pure farms to mixed or supplement farms. Consequently, less and less private forest owners will have the time, the practical experiences of forest management and sufficient knowledge in forestry, and thus in future a greater share of private forest owners will hire services offered by machinery rings. Therefore, the future public institution cooperation should be promoted based on the use of machinery.

4.2 Results of A’WOT method – Rezultati metode A’WOT SWOT analysis involved three presidents of machinery rings that deal exclusively with forestry in Slovenia. The results reflect the point of view of the presidents and are presented in Table 3. The strength of machinery ring is shown in the association of farmers and private forest owners who cooperate in the utilization of machinery, which is not limited only to the closest neighbors (inter-neighbor assistance) but is available for use in the whole area of the machinery ring (several villages, municipality). Furthermore, the head of the machinery ring knows the mechanization of members, passes on the information about needs and available capacities,

Table 3 SWOT analysis of machinery rings Tablica 3. SWOT analiza udru`enja za upotrebu mehanizacije STRENGHTS – SNAGE Integration of farmers and private forest owners Povezanost poljoprivrednika i privatnih {umovlasnika Knowing the level of mechanization of members Poznavanje razine mehanizacije kod ~lanova Education of private forest owners Obrazovanje privatnih {umovlasnika

OPPORTUNITIES – PRILIKE Partial professionalization of work Djelomi~na profesionalizacija rada Strengthening the operation of the machinery rings in the field of forestry Ja~anje operacija udru`enja u {umarstvu

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WEAKNESSES – SLABOSTI Realization of personal interests Postizanje osobnih interesa Not enough means for operation Nedovoljno sredstava za operacije Lack of time of the machinery ring president Nedostatak vremena predsjednika udru`enja za upotrebu mehanizacije S W O T THREATS – PRIJETNJE Competition among providers/members Konkurencija me|u dobavlja~ima/~lanovima Subsidies for equipment investments Poticaji za nabavu opreme Fostering the association of Slovenian public forestry service into other forms of cooperation – Poticanje udru`ivanja u druge oblike suradnje koje dolazi od javnoga {umarskoga servisa Slovenije

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and coordinates the collaboration of the clients and service providers. The strength is also that the members are trained and educated in the ring – for example forest machinery rings are active especially in the field of work safety in the forest, they attend machinery presentations, excursions, and courses. As all forms of cooperation are organized as a society and are operating on voluntary basis, machinery rings also have to deal with weaknesses such as personal interests of the members, poor financial means for operation, which decreases on a yearly basis, and a lack of time of the people in charge. Machinery rings receive financial means mainly through members’ fees, by co-financing by the Ministry of Agriculture, Forestry and Food, and by charging its services to non-members. Still, there is a lack of financial means to professionalize the position of the executive of the machinery ring (in Slovenia one executive has a part-time job, the rest work under contracts) (Dolen{ek 2008). This implies that Governmental institutions (especially the Ministry of Agriculture, Forestry and Food) should become more active in promoting cooperation in joint purchases and use of machinery and in supporting efforts for professionalizing such forms. However, a financial system should be established that will in its initial phase help machinery rings to start with semi professionalization and find a way to stimulate the employees of public institutions (e.g. possibilities for additional education, involvement in forestry excursions) to spread information and to promote cooperation of common machinery use. Due to the operation expansion and an increase of members (between 2006 and 2009, membership grew from 330 to 460 with the area collectively owned by these members similarly growing from 4.715 ha to 6.713 ha in three forestry machinery rings), it is not surprising that people in charge of machinery rings do not have enough time to do their tasks. Hence, the status of machinery rings must change. As mentioned above, the work in machinery rings should be professionalized, especially when a machinery ring gets enough members (more than 400) and when it reaches a sufficiently wide range of services (Dolen{ek 2008). This is recognized as the main opportunity for machinery rings. The opportunities are also reflected in improved activities in the field of forestry, especially with technological development and improved harvesting system. With modern and more highly mechanized forest machines, the investment costs increase. An increased need for machinery cooperation is expected in the future as these modern logistic concepts require a significant capital investment, which often exceeds the capacity of private forest owners, based on modest income from

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their small-scale forests. On the other hand, in machinery rings, the employment of forest contractors (one of the members) ensures forest tending, as small-scale private forest owners are insufficiently professionally, technically and financially skilled for the management of forests. If the members of a machinery ring provide the same services, internal competition can occur, which represents a threat for machinery ring operation. Subsidies for investments into equipment and machinery purchase are given only to bigger owners. This has an adverse effect on the owners with small-size properties but could nonetheless provide the same services to the members in a machinery ring. Obviously, the subsidies system should be changed so as to enable the members of machinery rings to apply for such subsidies provided that they undertake to work with such machinery in a machinery ring for the next five years. Recently, there has been a trend in the Slovenian public forestry service to stimulate the association of private forest owners into societies. However, this has a negative effect on machinery rings and can also be seen as a threat. To arrive to the final stage of A’WOT method, the priority vectors (w) and consistency rations (CR) of group comparison matrices were calculated for factors in SWOT groups. They are presented in Tables 4–7.

Table 4 Priority vector and consistency ratio of group comparison matrix of strengths Tablica 4. Vektor te`ine i omjer konzistencije za matricu usporedbe snage Strengths – Snage Integration of farmers and private forest owners – Povezanost poljoprivrednika i privatnih {umovlasnika Knowing the level of mechanization of members – Poznavanje razine mehanizacije kod ~lanova Education of private forest owners – Obrazovanje privatnih {umovlasnika

w 0.4844 0.4060 0.1095

CR=0.0347

Table 5 Priority vector and consistency ratio of group comparison matrix of weaknesses Tablica 5. Vektor te`ine i omjer konzistencije za matricu usporedbe slabosti Weaknesses – Slabosti Not enough means for operation – Nedovoljno sredstava za operacije Lack of time of the machinery ring president – Nedostatak vremena predsjednika udru`enja za upotrebu mehanizacije Realization of personal interests – Postizanje osobnih interesa

w 0.5821 0.2750 0.1430

CR=0.0003

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Table 6 Priority vector and consistency ratio of group comparison matrix of opportunities Tablica 6. Vektor te`ine i omjer konzistencije za matricu usporedbe prilika Opportunities – Prilike Strengthening the operation of the machinery rings in the field of forestry – Ja~anje operacija udru`enja u {umarstvu Partial professionalization of work – Djelomi~na profesionalizacija rada

w 0.8000 0.2000

CR=0.0000

Table 7 Priority vector and consistency ratio of group comparison matrix of threats Tablica 7. Vektor te`ine i omjer konzistencije za matricu usporedbe prijetnji Threats – Prijetnje w Subsidies for equipment investments – Poticaji za nabavu opreme 0.5168 Fostering the association of Slovenian public forestry service into other forms of cooperation 0.2470 Poticanje udru`ivanja u druge oblike suradnje koje dolazi od javnoga {umarskoga servisa Slovenije Competition among providers/members – Konkurencija me|u 0.2361 dobavlja~ima/~lanovima CR=0.0191

According to the results of SWOT factors, the factor with the highest priority is selected and it represents a group. The strengths were represented by the factor »Integration of farmers and private forest owners«, the weaknesses by »Not enough financial means for operation», the opportunities by »Strengthening the operation of machinery rings in the field of forestry«, and threats by the factor »Subsidies for equipment investments«. Furthermore the priority vectors (w) and consistency rations (CR) of group comparison matrices for SWOT groups are presented in Table 8. The analysis conducted according to A’WOT method showed that in order to establish the strate-

Table 8 Priority vector and consistency ratio of group comparison matrix of SWOT groups Tablica 8. Vektor te`ine i omjer konzistencije za matricu usporedbe grupa SWOT SWOT groups – SWOT grupe Strengths – Snage Weaknesses – Slabosti Opportunities – Prilike Threats – Prijetnje CR=0.0292

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w 0.0895 0.2836 0.2428 0.3840

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gic objectives, machinery rings have to minimize weaknesses (w = 0.2836) to avoid threats (w = 0.3840). A defensive approach to strategic planning was, therefore, applied to form suitable strategies. Such defensive formation of strategies represents a combination of the following strategic objectives: acquisition of financial means for the operation of machinery rings not only from the government, but also from self–promotion of the operation of machinery rings. This would provide the services offered to non–members who would pay a certain price in exchange. The promotion itself depends on the time of the people in charge, and therefore points into the direction of professionalizing the operation of larger machinery rings. In this way, the collaboration among members would improve and there would be less mistrust of the operation and fewer personal interests. If these weaknesses are surmounted, the members will try to influence the tenders for subsidiaries and take care of the promotion of machinery ring integration. In this case the fostering of integration by the Slovenian public forestry service into other forms of cooperation would not represent a threat anymore. Additionally, together with the improved operation of machinery rings, the competition among the service providers would decrease.

5. Conclusion – Zaklju~ak According to the results of our study, as well as previous experiences with A’WOT (e.g. Pykalainen et al. 1999, Ananda and Herath 2003, Wolfslehner et al. 2005, [egoti} et al. 2007), we can assent that the combined use of the AHP method and SWOT analysis is a promising approach in supporting strategic decision making processes. The evaluation of strategies with A’WOT method forces the decision makers to analyze the situation more precisely than in the cases where only the standard SWOT analysis is used. Machinery rings are nowadays an essential part of strategic (operational) management in Slovenian agriculture and forestry. However, there seem to remain many opportunities that are not fully exploited. In the future, it is necessary to expand the membership of machinery rings to new farmers and forest owners, to promote the services offered by members, to strengthen the operations in the field of forestry and to find new opportunities in the market, especially in the sense of cooperation between forest owners and forestry enterprises. All these facts enable members to operate efficiently, while using the newest technologies and to optimize the production costs.

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The optimal use of the available machinery and the exchange of farmer-to-farmer services should become tasks and prospects of Slovenian machinery rings. This endeavor ensures a cost efficient use of machinery – machinery management. However, machinery rings can offer much more to their members. Machinery rings can provide economic assistance, i.e. assistance at peak working season and social assistance, i.e. social operations in emergencies. Thus, with the expansion of services to private individuals, as for example winter service suppliers, companies, municipalities and public institutions, the members can gain additional income and labor opportunities.

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Plej, B., 2001: Strojni kro`ki. Diplomsko delo, Univerza v Mariboru, Fakulteta za kmetijstvo in biosistemske vede, samozalo`ba: 59 p. Pykalainen, J., Kangas, J., Loikkanen, T., 1999: Interactive decision analysis in participatory strategic forest planning: experiences from state owned boreal forests. Journal for economics, 5(3): 341–364. Rauch, P., 2007: SWOT analyses and SWOT strategy formulation for forest owners cooperaton in Austria. European Journal of Forestry Research, 126(3): 413–420. Robek, R., Klun, J., Medved, M., 2005: Mo`nosti tehnolo{kega razvoja pri pridobivanju lesa v dru`inskih gozdovih v Sloveniji.In: Prihodnost gospodarjenja z zasebnimi gozdovi v Sloveniji (Winkler, I.,ed.)., Biotehni{ka fakulteta, Oddelek za gozdarstvo in obnovljive gozdne vire, Ljubljana, Slovenia, p. 189–205. Saaty, T. L., 1980: Multicriteria Decision Making: The Analytic Hierarchy Process. McGraw-Hill, New York, 154 p. Saaty, T. L., 2003: Decision making with the AHP: Why is the principal eigenvector necessary. European Journal of Operational Research, 145(1): 85–91. Societies Act 2011: Official Gazette of the Republic Slovenia, NN 64/2011. Spinelli, R., Magagnotti, N., 2010: The effect of introducing modern technology on the financial, labour and energy performance of forest operations in the Italian alps. Forest policy and economics, 13(7): 520–524. Croat. j. for. eng. 33(2012)1

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darjenju {umama – modeli i izkustva. [umarski list 134 (5–6): 275–286. [por~i}, M., Landeki}, M., Lovri}, M., Martini}, I., 2011: Modeli planiranja i odlu~ivanja u {umarstvu. Croatian Journal of Forest Engineering 32(1): 443–456. [umi, J., 1977: Izkori{~anje in organizacija strojne skupnosti v naselju: Diplomsko delo, Univerza v Mariboru, Fakulteta za kmetijstvo in biosistemske vede, samozalo`ba: 39 p. Wolfslehner, B., Vacik, H., Lexer, M. J. 2005: Application of the analytic network process in multi-criteria analysis of sustainable forest management. Forest ecology and management, 207 (1–2): 157–170. Zgonjanin, @., 1987: Strojna skupnost Re~ica ob Paki. Diplomsko delo, Univerza v Mariboru, Fakulteta za kmetijstvo in biosistemske vede, samozalo`ba: 43 p.

Sa`etak

Sada{nje stanje i perspektive suradnje privatnih {umovlasnika Slovenije u udruènjima za upotrebu {umske mehanizacije U Republici Sloveniji prevladavaju privatne {ume. Razvoj i gospodarenje privatnim {umama povezani su s promjenama dru{tveno-ekonomske strukture privatnoga {umoposjeda, koje se o~ituju u smanjenju veli~ine privatnih posjeda, porastu broja {umovlasnika, niskom intenzitetu gospodarenja, neadekvatnoj opremi i nedovoljnoj upotrebi {umske mehanizacije. Za racionalno gospodarenje privatnim {umama i zadovoljavaju}u upotrebu mehanizacije potrebna je suradnja privatnih {umovlasnika, koja }e smanjiti tro{kove i omogu}iti upotrebu novih, suvremenijih na~ina {umskoga rada u privatnim {umama. Stanje i perspektive suradnje u upotrebi {umske mehanizacije u Republici Sloveniji analizirani su anketiranjem privatnih {umovlasnika i analizom A’WOT (SWOT + AHP analiza). Za anketiranje su ~lanovi udruènja za upotrebu {umske mehanizacije (dalje udruènja) podijeljeni u pet razreda prema veli~ini posjeda, a unutar tih razreda obavljen je sustavni izbor. Uzorak je obuhvatio 172 ~lana udruènja. Na anketu je odgovorilo 43,8 % ispitanika. Za identificiranje SWOT ~imbenika intervjuirani su predsjednici udruènja koja rade u {umarstvu. Predsjednici su izrazili svoje mi{ljenje o snagama, slabostima, prilikama i prijetnjama njihova djelovanja na gospodarenje privatnim {umama. Rezultati anketiranja pokazuju da su ~lanovi udruènja samo djelomi~no zadovoljni s njegovim djelovanjem. Razlog su tomu nedovoljne aktivnosti i informiranje o mogu}nostima upotrebe kapaciteta ostalih ~lanova, premalo ponu|enih aktivnosti i suradnje me|u ~lanovima te problemi s obra~unavanjem njihovih usluga. 93,9 % privatnih {umovlasnika u udruènju smatra da su njihovi interesi u vezi s gospodarenjem privatnom {umom zadovoljeni (tablica 2). Za ve}inu ~lanova udruènja su prikladan oblik suradnje u odnosu na njihove potrebe u gospodarenju {umom. Suradnja u udruènju ima budu}nost pogotovo ako se imaju na umu dru{tveno-ekonomske promjene iz ~istih u mje{ovita gospodarstva. Sve manje i manje privatnih {umovlasnika imat }e dovoljno vremena, prakti~noga iskustva i znanja za gospodarenje {umom. Zbog toga }e u budu}nosti ve}i dio privatnih {umovlasnika traìti informacije i unajmljivati usluge udruènja. Rezultati analize A’WOT pokazuju da je glavna snaga udruènja povezivanje poljoprivrednika i privatnih {umovlasnika (tablica 4), a slabost nedovoljna sredstava za provo|enje aktivnosti (tablica 5). Glavna je prilika ja~anje aktivnosti udruènja u {umarstvu (tablica 6), a prijetnja su nedovoljni poticaji za nabavu opreme, koji su dostupni samo velikim {umovlasnicima (tablica 7). Obrambeni pristup strate{koga planiranja primijenjen u obliku prikladne strategije udruènja pokazuje da je potrebno smanjiti slabosti kako bi se izbjegle prijetnje.

Croat. j. for. eng. 33(2012)1

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[. Pezdev{ek Malovrh et al.

The Present State and Prospects of Slovenian Private Forest Owners’ Cooperation ... (105–114)

Udruènja su danas neizostavni dio slovenske poljoprivrede i {umarstva, me|utim njihove se mogu}nosti nedovoljno koriste. U idu}em je razdoblju potrebno pro{iriti ~lanstvo na nove poljoprivrednike i {umovlasnike, promicati usluge ~lanova, ja~ati suradnju u {umarstvu i prona}i nove trì{ne mogu}nosti, osobito u suradnji me|u poduze}ima. To }e omogu}iti ~lanovima da rade gospodarski efektivno primjenom najnovije tehnologije i optimiziranjem tro{kova proizvodnje. Slovenska udruènja danas nude samo usluge koje se odnose na tro{kovno efektivnu upotrebu strojeva, a mogli bi ponuditi ~lanovima puno vi{e: gospodarsku i socijalnu pomo}. Klju~ne rije~i: suradnja u upotrebi mehanizacije, udruènja {umske mehanizacije, privatne {ume, anketiranje, metoda A’WOT, strate{ko planiranje

Authors’ address – Adresa autorâ: [pela Pezdev{ek Malovrh, PhD. e-mail: spela.pezdevsek.malovrh@bf.uni-lj.si Prof. Lidija Zadnik Stirn, PhD. e-mail: lidja.zadnik@bf.uni-lj.si, PhD. Prof. Janez Kr~, PhD. e-mail: janez.krc@bf.uni-lj.si Biotechnical Faculty Department of forestry and renewable forest resources Ve~na pot 83 1000 Ljubljana

Received (Primljeno): September 13, 2011 Accepted (Prihva}eno): November 21, 2011

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SLOVENIA Petra Gro{elj, Msc. e-mail: petra.groselj@bf.uni-lj.si Biotechnical Faculty Department of wood science Cesta VIII/34 1000 Ljubljana SLOVENIA Croat. j. for. eng. 33(2012)1

Original scientific paper â&#x20AC;&#x201C; Izvorni znanstveni rad

Productivity Linear Regression Models of Tree-Length Harvesting System in Natural Coastal Aleppo Pine (Pinus halepensis L.) Forests in the Chalkidiki Area of Greece Christos Gallis, Gavriil Spyroglou Abstract â&#x20AC;&#x201C; Nacrtak Time studies of harvesting and skidding tree-length logs in Aleppo pine (Pinus halepensis L.) natural coastal forests of Chalkidiki area in northern Greece were carried out to formulate linear regression models and to evaluate productivity. The harvesting system consisted of a feller with chainsaw for felling, delimbing and crosscutting, and a four wheel drive farm tractor, with a 74 kW engine, equipped with a special winch attached to the tractor three point hitch for the extraction of tree length logs. Operational factors such as distance, slope, volume and the time required for harvesting and extracting tree length logs were measured and recorded. The results illustrate that the calibrated linear regression models show strong correlation between the time needed for harvesting operations and the extraction distance from the stump to the forest road. Keywords: tree length system; extraction; time studies; linear regression models; productivity; Aleppo pine; natural coastal forests

1. Introduction â&#x20AC;&#x201C; Uvod The forest biomass industry operates under severe economic pressure for lower production costs. One way to lower the pressure is the most effective cost control of raw material (Bushman and Olsen 1988, Gallis 1997, Gallis 2003). Timber cost has been a topic of continuous concern for forest managers and forest products industry. Technical and economic utilization of forest biomass depends on various factors related to terrain conditions, transportation networks and harvesting technologies, as well as systems, silviculture and forest operations management (Cavalli and Grigolato 2010, Picchio et al. 2011). Working time studies are very often used for the analysis of productivity of various forest biomass harvesting systems (Gallis 2004, Magagnotti et al. 2012, Picchio et al. 2009, Savelli et al. 2010, Spinelli and Nati 2009). Thus collected data may be used to formulate regression models for the correlation of several parameters of the harvesting system with time and productivity (Cubbage et al. 1988, Gallis 1997, Gallis 2004, Gingras 1988, Katenidis et. al. 1983). Croat. j. for. eng. 33(2012)1

These models could be used for planning and economical analysis of forest operations (Howard 1988, Samset 1990, Gallis 2004). The harvesting and removal of forest biomass from the natural forests of Greece requires a profitable and environmentally acceptable logging system. This system should be able to thin and remove individual trees from even aged stands with dense understory of evergreen broadleaved shrubs or uneven-aged stands, and to harvest mature trees. The most critical stage of the logging operation is forwarding logs from the forest site to the roadside landings. It may account up to 30% of the total harvesting cost and can cause some environmental damages (Fisher et al. 1980, Gallis 2003, Picchio et al. 2011, Spinelli et al. 2010). Currently in Greece, the main system widely employed is felling, delimbing, topping and crosscutting trees with a chainsaw in the stump area and extracting medium and small-sized logs from the forest site to roadside landings by special vehicles, farm tractors and horses. The use of tree length system has been

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Productivity Linear Regression Models of Tree-Length Harvesting... (115–123)

recently introduced in Greek forestry mainly in stands with terrain of low inclination. Modified farm tractors are currently used for wood extraction. In the tree length system, trees are usually extracted with a part of the load dragged along the ground with a cable winch attached to the rear system of the farm tractor (winching operation). Farm tractors may have some advantages such as increased flexibility for other types of work, and lower capital investment. The flexibility and relatively low capital input can reduce the need to maintain high productivity and annual utilization (Johansson 1997). Further research of skidding operations time studies for tree length system operations is required in Greece. The aim of this study was to calibrate regression models through working time studies in order to define the effect of stand and operational factors such as distance, slope, and volume on time of harvesting and on extracting tree length logs from the forest site to the forest road. The study was carried out in the coastal Aleppo pine (Pinus halepensis) natural forests of Sithonia peninsula of Chalkidiki area in northern Greece.

2. Materials and methods – Materijal i metode The working time studies were conducted in several different uneven-aged Pinus halepsinis stands and they examined the harvesting and extraction cycles. The harvesting system applied consisted of selecting individual trees, one by one, through high thinning positive selection. More specifically, in each stand, the plus or future trees are identified intuitively on a regular distribution pattern by the forester in charge and, according to the silvicultural descriptions of the management plan, one or two trees – competitors are marked for felling (Chatziphilippidis and Konstandinidis, 1995). The marked trees were felled, delimbed and topped by a chainsaw in the stump area. The extraction was carried out by a four wheel farm tractor, with a 74 kW engine, equipped with a special winch attached to the tractor three point hitch. The stands under study had no strip roads for extraction. Thus, the operation was performed with the farm tractor moving on the forest ground. The system of harvesting-extraction with farm tractors consists of a driver and a feller. In several stands, time studies were performed in order to calculate the time required for the extraction of one tree length log from the stand to the roadside landing. The timing method used in this study was the continuous method. According to this method the watch is in continuous motion and the position of the time

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indicator is recorded at the beginning of each work phase or delay and at the end of the total work under study (Tsoumis and Efthymiou 1973, Barnes 1980, Niebel 1988, Tsoumis 1992, Gallis 1997, Gallis 2004). The starting point for timing the extraction cycle was when the team departed from the roadside to the stand for loading. An operator performed the harvesting operations assisted by the driver. The time was recorded for each cycle element: travelling empty to the place of loading, felling, delimbing, waiting to be loaded, using the winch for loading, travelling with the load, arriving at the landing, waiting to be unloaded, unloading, and cross cutting. In addition to time measurements, other parameters were also recorded for each cycle such as the volume of tree length logs, the distance from the landing to the loading point, and the slope. For every full cycle of harvesting-extraction operation, the full cycle and the harvesting time productivity were calculated as cubic meters of tree volume harvested per hour. 30 complete cycles were recorded (Table 1) in total. For each numbered log, the volume was calculated using the formula of truncated cone. Simple linear models (linear regression models) in the form Y (Time of logging operation) = f (Slope, Distance, Log volume) were selected. The development of model equations for each category of logging operation time was Y = a + b · Sl + c · Dist + d · LogVol, where Y is the Time needed for logging operations in minutes, Sl is the terrain slope in (%), Dist is the distance of the logging site to the forest roadside landings in meters and LogVol is the volume of the logs forwarded from the logging site to the forest roadside landings in cubic meters. The statistical analysis was performed by using the computer statistical program SPSS 12.0 (Norusis 2003).

3. Results and discussion – Rezultati i rasprava The average slope of the study area was 4.6% denoting a rather flat terrain where a farm tractor can be easily used for harvesting operations without a risk of erosion on the skidding roads. The mean extraction distance was 84.17 m and the mean extracted log volume was 1.95 m3 resulting in a mean harvesting time of 6 minutes and 9 seconds, which corresponds to 42.1% of the total time. The mean extraction time was 3 minutes and 29 seconds, meaning that almost 24% of the total time was spent for this operation. Travelling empty time was 1':17'' representing 8.7% of the total time of the harvesting operation. The total time for a complete cycle ranged from 10 minutes and 27 seconds to 28 minutes and 36 seconds with an average of 14 minutes and 36 seCroat. j. for. eng. 33(2012)1

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Table 1 Descriptive statistics of the slope, distance, log volume and times needed for logging operations Tablica 1. Deskriptivna statistika nagiba terena, udaljenosti, obujma sortimenta i utro{ka vremena pridobivanja drva Variable Varijabla

N N

Min. Min.

Max. Maks.

Mean Arit. sred.

Std. Dev. St. dev.

4.60

1.45

207

84,17

50.67

Log Volume – Obujam sortimenta, m

6.33

1.95

0.97

Preparation – Priprema za rad, min:sec

0.95 0:06

1:24

0:47

0:30

Felling – Ru{enje, min:sec

Slope – Nagib, % Distance – Udaljenost, m 3

0:42

2:36

1:10

0:54

Delimbing – Kresanje grana, min:sec

2:09

8:06

4:14

1:40

Skidding – Privla~enje, min:sec

1:42

6:03

3:29

1:21

Cross cutting – Trupljenje, min:sec

1:42

12:42

4:09

2:15

Travelling empty – Neoptere}ena vo`nja, min:sec

0:36

2:30

1:17

0:51

10:27

28:36

14:36

3:54

3:42

11:48

6:09

2:19

4.9

9.9

7.5

1.3

10.8

32.2

18.5

4.5

Total time – Ukupno vrijeme, min:sec Harvesting time – Vrijeme sje~e, min:sec 3

Full cycle productivity – Proizvodnost cijelokupnoga procesa, m /h 3

Harvesting time productivity – Proizvodnost sje~e, m /h

conds. Katenidis (1978) reports that the travelling empty time consumed one half (50%) of the harvesting time required when mules were used as animals for extraction and 25% of the total time used for skidding. The use of machines instead of animals, whenever feasible, reduces considerably the extraction as well as the travelling empty time. The harvesting time and the full cycle productivity ranged between 10.8 to 32.2 and 4.9 to 9.9 m3 per hour with a mean value of 18.5 and 7.5 m3 per hour, respectively. Descriptive statistics of the slope, distance, log volume and the necessary times used in logging operations are presented in Table 1. After the application of linear regression procedure on the above mentioned models, the adjusted results are shown in Table 2. Model 1 is for the full cycle operation, Model 2 for travelling empty and Model 3 for travelling with the load (skidding). For travelling empty (2) and skidding (3) models, the only statistically significant independent variable was the distance, the other two variables, slope and log Table 2 Linear regression model equations to predict logging time operations Tablica 2. Linearne regresijske jednad`be modela za predvi|anje utro{ka vremena pridobivanja drva Model Model

Equation Jednad`ba

Tfull = 6.434 + 0.023 · Distance + 3.082 · Log volume

Tempty = 0.366 + 0.009 · Distance

Tforwarding = 1.909 + 0.012 · Distance

Croat. j. for. eng. 33(2012)1

volume appeared non-significant because for slope, there is no much variability within the variable (2–8%) and for the log volume, the 74 kW farm tractor with its 4100 kg mass used for skidding was strong enough to carry out the logging without any delays due to log size and weight. If we suppose that the tractor was moving by a more or less constant velocity, when skidding or when travelling empty from the forest road to the logging site, then the distance was the only driving variable for the time needed for the operations. For model (1), the independent variable slope was not statistically significant for the reason explained above, and hence it was removed from the model. The log volume variable plays an important role accounting for a large proportion of the observed variance (partial adj. R2=0.64). This can be attributed to the fact that the full cycle time includes harvesting operations (felling and delimbing) that represent 42.1% of the full cycle operation, making this variable highly significant. Johansson (1997), in his study on small tree harvesting by use of farm tractors with the crane attached to the front part, when doing regression analysis of time consumption per work cycle, found that the tree volume was the only variable that accounted for a large proportion of the variation in time consumption and that there was no reason to use a more sophisticated model than that of the simple regression. Table 3 shows that all regression models have large correlation coefficients as well as coefficients of determination. All the models performed very well,

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and the variance explained by the models varied from 74 percent for the full cycle model (1) to 24 percent for the forwarding (3). The Durbin-Watson statistic is between 0.81 and 2.04. For models (1) and (3), the Durbin-Watson statistic falls within the range 1.5 to 2.5 and the assumption of residuals independence is satisfied for these models. For model (2) the Durbin-Watson statistic was 0.81 indicating a positive autocorrelation. Autocorrelation is the phenomenon that distinguishes time series from other branches of statistical analysis. For example, if we consider the tractor operator during the travelling empty time. A usual time cycle varies around one minute and seventeen seconds. The variation may be caused by machine failure; the dense understorey of evergreen broadleaves characteristic for Allepo pine stands sometimes prevents the operator from keeping a constant tractor speed, resulting in a run of increased travelling empty time cycle. This is an example of positive autocorrelation, determined by the Durbin-Watson statistic for model 2 (0.81), with data falling and staying below one minute and seventeen seconds for a few cycles especially when the understorey vegetation is very dense obliging the tractor operator to reduce a bit the moving speed, then rising above one minute and seventeen seconds and staying high for a while, then falling again, and so on.

Table 4 shows the model coefficients and their significance denoting strong models. The slope variable, represented by the (b) parameter in all models appeared non significant by the regression analysis and is not included in the table. The same holds for the log volume variable, represented by the (b) parameter for models 2 and 3. Multicollinearity is not a problem for the models because the tolerance statistic was very close to 1, much greater than 0.1, which is considered the threshold for multicollinearity problems. The variance inflation factor (VIF) was also around 1 and certainly less than the threshold value of 5 (Van Laar 1991). In order to visualize the relationships among the dependent and independent variables of the calibrated models, three and two dimensional scatter plots were drawn. Fig. 1 shows the strong positive linear relationship that exists among the dependent variable time of various logging operations and the independent variables, distance and log volume. The three models were also checked for heteroscedasticity, the third assumption of the linear regression – assumption of constant error variance. The residual analysis of the models 1 & 3 in Fig. 2 shows that there were no obvious patterns or clustering in the residuals, the residuals were homoscedastic, and the variance remained the same for every combination of values of the independent va-

Table 3 Statistical summary of the studied models Tablica 3. Statisti~ki sa`etak ispitivanih modela Model Model

1 2 3

0.87 0.94 0.49

0.76 0.89 0.24

Adjusted R2 Prilago|eni R2 0.74 0.88 0.21

SE of estimate Stand. pogre{ka procjene 1.81 0.17 1.07

Durbin-Watson 1.65 0.81 2.04

Table 4 Model coefficient estimates and collinearity diagnosis Tablica 4. Procjena koeficijenata i dijagnoza kolinearnosti za modele Model Model 1

2 3

Tolerance Tolerancija

VIF FPV

6.543

Sig. Razina zna~. 0.000

0.007

3.414

0.002

0.988

1.012

0,348

0.885

0.000

0.988

1.012

0.061

5.974

0.000

0.001

15.145

0.000

1.00

1.909

0.385

4.955

0.000

0.012

0.004

2.956

0.006

1.00

Parameters Parametri

Coefficients Koeficijenti

SE Stand. pogre{ka

T T

6.434

0.983

c d

0.023

3.082 0.366

0.009

a c

Sig. – 0.000 means that the coefficient of the model is highly significant; Razina zna~. – 0,000 razumijeva da su koeficijenti modela visoko zna~ajni VIF – Variance Inflation Factor; FPV – Faktor pove}anja varijance

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Fig. 1 Scatter plots between dependent and independent variables of the three models Slika 1. To~kasti grafikoni zavisnih i nezavisnih varijabli za tri modela riables. Model 2 shows a slight clustering and as it can be seen in Table 5, the Kolmogorov-Smirnov and Shapiro-Wilk tests for the normality of the residuals appear statistically significant, meaning that either the relationship in model 2 is not linear or that there is another variable causing more variability, which was not considered or measured during data collection. The autocorrelation exhibited by the same Croat. j. for. eng. 33(2012)1

model might be another source of the clustering in the residuals. The assumption of normality was another issue that had to be tested in order to secure that the calibrated models are statistically sound. The statistical criteria of Kolmogorov-Smirnov and Shapiro-Wilk shown in Table 5 appear statistically non-significant at a = 0.05 level except Model 2, for which

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Productivity Linear Regression Models of Tree-Length Harvesting... (115â&#x20AC;&#x201C;123)

Fig. 2 Residual analysis of the three models Slika 2. Analiza rezidualnih odstupanja za tri modela the criteria appeared significant. This deviation from normality was not a big problem and hence did not interfere with the regression analysis.

4. Conclusions â&#x20AC;&#x201C; Zaklju~ci From the present study, the following conclusions can be drawn:

120

1. The modified farm tractors can be operated in tree length harvesting with flexibility and good productivity in natural stands with low inclination and without strip roads. 2. The calibrated regression models show strong correlation between the time needed for harvesting operations and the extraction distance from the stump to the forest road. Croat. j. for. eng. 33(2012)1

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Christos Gallis and Gavriil Spyroglou

Table 5 Tests of normality of the residuals for the studied models Tablica 5. Testovi normalnosti rezidualnih odstupanja ispitivanih modela Model Model

Statistic Statistika

0.114

df St. sl. 30

0.186

0.118

Shapiro-Wilk

Kolmogorov-Smirnov Sig. Razina zna~.

0.200 ns 0.010* 0.200

Statistic Statistika 0.964

df St. sl. 30

Sig. Razina zna~.

0.866

0.384 ns 0.001**

0.958

0.267 ns

– The respective statistic is non-significant; ns – nema zna~ajne razlike * – Significant at alpha level (or P-value) = 0.05; * – zna~ajna je razlika za vrijednost p = 0,05 **– Significant at alpha level (or P-value) = 0.001; ** – zna~ajna je razlika za vrijednost p = 0,001

Further studies are needed to define the impact of site and stand conditions such as steeper slopes, mixed forests, mountain forests, stands with strip roads, as well as other related operations such as delimbing and crosscutting, for more consistent and sound time study models for tree length harvesting system covering all types of forests in Greece.

Acknowledgements – Zahvale This study was financially supported through the grant for »New Researchers« of the National Agricultural Research Foundation (NAFREF) of Greece (2002).

5. References – Literatura Barnes, R. M., 1980: Motion and time study: design and measurement of work. 7th ed., John Wiley and Sons, New York, 689 p. Bushman, S., Olsen, E. D., 1988: Determining Costs of Logging-Crew Labor and Equipment. Oregon State University, College of Forestry, Forest Research Lab, research Bulletin 63, 23 p. Cavalli, R., Grigolato, S., 2010: Influence of characteristics and extension of a forest road network on the supply cost of forest woodchips. Journal of forest research 15(3):202– 209. Chatziphilippidis, G., Konstandinidis, P., 1995: !D"4éFg4l 6"4 68"*gbFg4l *"F46f< FLFJV*T< (Thinning and pruning of forest stands). AD"6J46V &@L A"<g88Z<4@L )"F@8@(46@b FL<g*D\@L :g 2X:" “)"F46Z !<VBJL>0, 3*4@6J0F4"6` – PTD@J">46`” O"<4V, 6-8 !BD48\@L 1994. In: Hellenic Forestry Society (ed.) Proceedings of the 6th Pan-Hellenic silvicultural congress »Forest development, land ownership – land use planning«, Chania, Greece, 6-8 April 1994, pp. 327–336. Cubbage, F. W., Wojtkowski, P. A., Bullard, S. H., 1988: Cross-sectional estimation of empirical southern United Croat. j. for. eng. 33(2012)1

States pulpwood harvesting cost functions. Canadian Journal Forest Research, 19(6): 759–767. Gallis, C., 1997: Stochastic Computer Simulation of Forest Biomass Logistics in Greece. Doctoral dissertation, Dept. of Forest Resource Management, University of Helsinki, Finland, 139 p. Gallis, C., 2003: Probabilistic assessment of forest biomass storage time and its effect on cost: a beech wood case study. Forest products journal 53(10): 44–47. Gallis, C., 2004: Comparative cost estimation for forwarding small-sized beech wood with horses and mini-skidder in northern Greece. Forest products journal 54(11): 84–90. Gingras, J. F., 1988: The effect of site and stand factors on feller-buncher performance. Forest Engineering Research Institute of Canada, Technical Report No. TR-84, 18 p. Greek Forest Service, 1994: I4:Xl L8@J@:4f< 6"4 V88 T< gD("F4f< FL(6@:4*ZH (Prices for felling and other harvesting operations). KB@LD(g\@ 'gTD(\"H, 'g<46Z )4gb2L<F0 )"Ff< 6"4 MLF46@b AgD4$V88@<J@H. Ministry of Agriculture, General Directorate of Forests and Natural Environment, Dept. of Forest and Natural Environment, Athens, 18 p. Fisher, E. L., Gibson, H. G., Biller, C. J., 1980: Production and Cost of a Live Skyline Cable Yarder Tested in Appalachia. U.S. Dept. of Agriculture, Forest Service, Northeastern Forest Experimental Station, Forest Service Paper NE-465, 7 p. Howard, A. E., 1988: Harvesting profitability as affected by classification of costs and assignment of the components scheduled time. Canadian journal forest research 18(11): 1369–1375. Johansson, J., 1997: Small trees harvesting with farm tractor and crane attached to the front. International journal of forest engineering 8(1): 21–33. Katenidis, K. B., 1978: 9gJ"J`B4F0 >b8@L 6T<@n`DT< :g :@L8VD4" FJ" +880<46V )VF0. (Soft wood skidding by mules in Greek forests). K:@LD(g\@ 'gTD(\"H, 3<FJ4J@bJ@

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Productivity Linear Regression Models of Tree-Length Harvesting... (115–123)

)"F46f< +DgL<f< !20<f<. Ministry of Agriculture, Athens Forest Research Institute, Research Bulletin No. 98, 38 p. Katenidis, K. B., Efthymiou, P.Í., 1983: 9g8XJ0 JT< L8@J@: 46f< gD("F4f< FJ" +880<46V *VF0 @>LVH )"F46Z WDgL<" 3: 165–217. (Research on Wood Felling and Conversion Operations in the Beech Forests of Greece). Forest Research 3: 165–217. Magnagnotti, N., Pari, L., Spinelli, R., 2012: Re-engineering firewood extraction in traditional Mediterranean coppice stands. Ecological engineering 38(1): 45–50. Niebel, B.W., 1988: Motion and time study. 8th ed., Irwin, Homewood, Illinois, 799 p. Norusis, M., 2003: SPSS 12.0 Statistical Procedures Companion. Prentice Hall. Picchio, R., Maesano, M., Savelli, S., Marchi, M., 2009: Productivity and Energy balance in conversion of a Quercus cerris L. Coppice stand into High forest in Central Italy. Croatian journal of forest engineering 30 (1): 15–26. Picchio, R., Spina, R., Maesano, M., Carbone, F., Lo Monaco, A., Marchi, E., 2011: Stumpage value in the short wood system for the conversion into high forest of a oak coppice. Forestry studies in China 13(4): 252–262. Picchio, R., Neri, F., Maesano, M., Savelli, S., Sirna, A., Blasi, S., Baldini, S., Marchi, E., 2011: Growth effects of thinning damage in a Corsican pine (Pinus laricio Poire) stand in central Italy. Forest ecology and management 262(2): 237–243.

Samset, I., 1990: Some observations on time and performance studies in forestry. Communications of the Norwegian Forest Research Institute No 43. 5, As, 80 p. Savelli, S., Cavalli, R., Baldini, S., Picchio, R., 2010: Small scale mechanization of thinning in artificial coniferous plantation. Croatian journal of forest engineering 31(1): 11–21. Spinelli, R., Nati, C., 2009: A low investment fully mechanized operations for pure selection thinning of pine plantations. Croatian journal of forest engineering 30(2): 89–97. Spinelli, R., Magagnotti, N., Nati, C., 2010: Benchmarking the impact of traditional small-scale logging systems used in Mediterranean forestry. Forest ecology and management 260(11): 1997–2001. Tsoumis, G., Efthymiou, P., 1973: WDgL<" FL(6@:4*ZH >b8`H FJ@ A"<gB4FJ0:4"6` *VF@H I">4VDP0 O"864*46ZH. +B4FJ0:@<46Z +BgJ0D\*" J@L !D4FJ@JX8g4@L A"<gB4FJ0:\oL 1gFF"8@<\60H I`:@H 3GI: 273–296. (A study on harvesting oak wood in the University forest at Taxiarchis, Chalkidiki-Greece). Scientific Annals, School of Agriculture and Forestry, Aristotle University of Thessaloniki, Greece, 16: 273–296. Tsoumis, G., 1992: Harvesting Forest Products. Stobart Davies Ltd., Hertford, England, 57 p. Van Laar, A., 1991: Forest Biometry. University of Stellenbosch, 590 p.

Sa`etak

Linearni regresijski modeli proizvodnosti pridobivanja drva deblovnom metodom iz prirodnih obalnih {uma alepskoga bora u predjelu Chalkidiki u Gr~koj Studij vremena pri sje~i i privla~enju obloga drva uz primjenu deblovne metode u prirodnim obalnim {umama alepskoga bora (Pinus halepensis L.) u predjelu Chalkidiki u sjevernoj Gr~koj proveden je radi dobivanja linearnih regresijskih modela i procjene proizvodnosti. Sustav pridobivanja drva ~inili su sjeka~ s motornom pilom za ru{enje, kresanje grana i prevr{ivanje, dok je za privla~enje obloga drva kori{ten prilago|eni poljoprivredni traktor koji je imao pogon na sva ~etiri kota~a, snagu motora 74 kW i posebno vitlo pri~vr{}eno u trima to~kama na stra`njem dijelu vozila. Operativni ~imbenici, na primjer: udaljenost, nagib terena, obujam oblovine, utro{ak vremena sje~e, izradbe i privla~enja, izmjereni su i zabiljeèni. Cilj je ovoga istraìvanja bio pobolj{avanje regresijskih modela pomo}u studija rada i vremena s namjerom definiranja utjecaja sastojinskih i operativnih ~imbenika kao {to su: udaljenost privla~enja, nagib terena i obujam drva na utro{ak vremena sje~e, izradbe i primarnoga transporta iz sje~ine do pomo}noga stovari{ta ({umske ceste). U istraìvanom sustavu pridobivanja drva usporedno su radili voza~ traktora i sjeka~. U nekoliko sje~ina proveden je studij vremena radi izra~una vremena potrebnoga za privla~enje pojedinoga debla iz sje~ine do {umske prometnice. Pri snimanju radnoga procesa primijenjena je proto~na metoda kronometrije. Polazi{na to~ka studija vremena radnoga turnusa privla~enja drva bio je trenutak kada je vozilo krenulo s pomo}noga stovari{ta u sastojinu radi utovara drva. Jedan je radnik sjekao stabla uz povremenu pomo} voza~a traktora. Vrijeme je bilo zabiljeèno za

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Productivity Linear Regression Models of Tree-Length Harvesting... (115â&#x20AC;&#x201C;123)

Christos Gallis and Gavriil Spyroglou

svaku sastavnicu radnoga turnusa: vo`nja neoptere}enoga vozila do mjesta utovara, sje~a stabala, kresanje grana, ~ekanje na utovar, skupljanje obloga drva vitlom (privitlavanje), vo`nja optere}enoga vozila, dolazak na pomo}no stovari{te, ~ekanje na odvezivanje tovara, odvezivanje tovara (istovar) i prikrajanje radi izrade drvnih sortimenata. Rezultati istra`ivanja pokazuju da su pobolj{ani modeli linearne regresije ~vrsto povezani s vremenom potrebnim za sje~u i s udaljeno{}u vo`nje iz sje~ine do {umske ceste. Ovo je istra`ivanje pokazalo da se prilago|eni poljoprivredni traktori mogu koristiti u deblovnoj metodi izradbe drva za primarni transport uz odre|ene prilagodbe i postizati zadovoljavaju}a proizvodnost u prirodnim sastojinama gdje su manji nagibi terena i koje nisu sekundarno otvorene (nema {umskih vlaka i traktorskih putova). Tako|er, pobolj{ani regresijski modeli pokazuju jaku ovisnost utro{ka vremena radova pridobivanja drva o udaljenosti privla~enja iz sje~ine do {umske ceste. Klju~ne rije~i: deblovna metoda, privla~enje, studij vremena, linearni regresijski modeli, proizvodnost, alepski bor, prirodne obalne {ume

Authors' address â&#x20AC;&#x201C; Adresa autora:

Received (Primljeno): November 25, 2011 Accepted (Prihva}eno): February 8, 2012 Croat. j. for. eng. 33(2012)1

Christos Gallis, PhD e-mail: cgalis@fri.gr Gavriil Spyroglou, PhD e-mail: spyroglou@fri.gr Forest Research Institute 570 06 Vassilika, Thessaloniki, GREECE

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Original scientific paper – Izvorni znanstveni rad

Improving Accuracy in Earthwork Volume Estimation for Proposed Forest Roads Using a High-Resolution Digital Elevation Model Marco Contreras, Pablo Aracena, Woodam Chung Abstract – Nacrtak Earthwork usually represents the largest cost component in the construction of low-volume forest roads. Accurate estimates of earthwork volume are essential to forecast construction costs and improve the financial control of road construction operations. Traditionally, earthwork volumes are estimated using methods that consider ground data obtained from survey stations along road grade lines. However, these methods may not provide accurate estimates when terrain variations between survey stations are ignored. In this study, we developed a computerized model to accurately estimate earthwork volumes for the proposed forest roads by using a high-resolution digital elevation model (DEM). We applied our model to three hypothetical forest road layouts with different ground slopes and terrain ruggedness conditions. We examined the effects of various cross-section spacings on the accuracy of earthwork volume estimation assuming that 1-meter spacing provides the »true« earthwork volume. We also compared our model results with those obtained from the traditional end-area method. The results indicate that as cross-section spacing increases the accuracy of earthwork volume estimation decreases due to lack of the ability to capture terrain variations. We quantified earthwork differences, which increased with terrain ruggedness ranging from 2 to 21%. As expected, short cross-section spacing should be applied to improve accuracy in earthwork volume estimation when roads are planned and located on hilly and rugged terrain. Keywords: forest roads, earthwork volume, road design, LiDAR, digital elevation model

1. Introduction – Uvod Earthwork usually represents the major cost component in the construction of low-volume forest roads, accounting for over 80 percent of the total construction cost on steep terrain (Stückelberger et al. 2006). It is essential to accurately estimate earthwork volumes to improve cost control and budgeting in forest road construction. Traditionally, ground information for the proposed roads is collected through a preliminary road centerline survey, where survey stations are placed usually at every 30 meters or at major gradient or direction changes to reduce expensive and labor-intensive field work. Ground slopes measured at each station is used to calculate cut and fill areas, which are then used to estimate earthwork volumes between consecutive cross-sections. Croat. j. for. eng. 33(2012)1

Earthwork volumes have been conventionally estimated using the average end-area or the prismoidal method (Hickerson 1964). Both methods require cross-section areas to be of the same type; either cut or fill. Epps and Corey (1990) developed procedures to estimate earthwork volumes differently for various configurations (cut and/or fill) of cross-section areas using the average end-area method. For linear ground profiles, the prismoidal method is known to provide more accurate estimates while the average end-area method generally overestimates earthwork (Epps and Corey 1990). Easa (1992a) developed a modified prismoidal method for estimating volumes on non-linear ground profiles. This method is based on the Pappus's theorem and estimates earthwork volumes approximately as the average of the volumes resulting from rotating both cross-section areas about an axis on their respective planes (see

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Hickerson 1964 for more details). The Pappus-based method provides accurate estimates only when the two cross-sections are also of the same type (either cut or fill). Easa (1992b) also developed a mathematical method based on triple integration that can deal with transition road segments where one of two consecutive cross-sections has both cut and fill areas, while the other has only either one. This method is complicated and applicable only for road segments where the ground profile is linear (Aruga et al. 2005). These existing earthwork volume estimating methods assume that the ground slope at each road cross-section is constant, which is unlike for most hilly and mountainous terrains. Kim and Schonfeld (2001) developed two methods to estimate cross-section areas more precisely. These methods use an interpolation method (inverse distance-weighted) to obtain elevation data, and vector and parametric representation of cross-sections to account for irregular ground slopes. The accuracy of all aforementioned methods seems to improve as the distance between consecutive cross-sections decreases (Kim and Schonfeld 2001). However, cross-sections can only be derived at survey stations, and an assumption about the homogeneity of ground slopes between consecutive cross-sections has to be made. High-resolution DEMs derived from the light detection and ranging (LiDAR) technology have recently been incorporated into forest road planning and design to increase accuracy in volume estimation by using the elevation data of each raster grid cell. LiDAR technology is known to provide accurate estimates of ground surface elevation even under a dense canopy cover (Reutebuch et al. 2003). Coulter et al. (2001) applied a 1-meter resolution LiDAR-derived DEM to estimate earthwork volumes for a proposed forest road. In this method, road elevation was assigned to each grid cell within the road template to estimate earthwork volume from the difference between road and ground surface elevations. However, this simplistic method is only applicable to straight road segments. Aruga et al. (2005) developed a computer program for forest road design that also uses a 1-meter resolution DEM. Their model precisely generates cross-sections and calculates areas, and accurately estimates earthwork volumes. As the actual ground profile can be represented more accurately when a shorter distance between cross-sections is applied (Aruga et al. 2005), earthwork volume estimations using a 1-meter resolution DEM were considered »exact« and comparable with other estimates obtained from different cross-section spacings and different estimation methods. The study was focused on the optimization of road design, and, however, limited emphasis was

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put on numerical procedures and the study does not provide a thorough analysis of the effects of cross-section spacing on earthwork volume estimation. Although the accuracy of earthwork volume estimates is expected to increase with decreasing spacing between consecutive cross-sections, to our knowledge, there are no studies evaluating and quantifying the differences in earthwork volume estimates in various terrain conditions. In this study, we developed a computerized model to accurately estimate earthwork volumes for the proposed forest roads using a high-resolution LiDAR-derived DEM. We examined the effects of cross-section spacings on the accuracy of earthwork volume estimation by applying the model to the proposed roads in various areas under different terrain conditions and estimating earthwork volumes of the roads at different cross-section spacings. Similar to Aruga et al. (2005), we assumed that 1-meter cross-section spacing provided the »true« earthwork value in our study. Our computerized model was applied to three hypothetical forest roads laid out on low, moderate, and steep slope areas, and the earthwork volume estimates from the model were compared with those from the traditional end-area method, which considers only the cross-sections located at survey stations. Lastly, comparisons were also made on road sections with three levels of terrain ruggedness.

2. Computerized model – Ra~unalni model The computerized model developed in this study was designed to accurately estimate cut and fill volumes for a proposed forest road using a high-resolution DEM. The main input data for the model include: i) an ASCII text file representing the LiDAR-derived DEM for the area of interest, and ii) a text file representing the x- and y-coordinates of sequential survey station points along a proposed road. Based on the cell size (1 meter in our applications) and the x-and y-coordinates of the lower left corner of DEM, the model calculates x- and y-coordinates of each grid cell in the DEM. These coordinates are used to obtain the ground elevation of each survey station point along the proposed road gradeline.

2.1 Estimating ground elevation – Procjena visine terena Starting from the beginning-of-project (BOP), ground elevations for each survey station point (SP) are obtained from the LiDAR-derived DEM. As DEM elevation values represent the elevation at the center of the grid cell and since a given SP might not coCroat. j. for. eng. 33(2012)1

Improving Accuracy in Earthwork Volume Estimation for Proposed Forest Roads ... (125–142)

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Fig. 1), and the other three adjacent cells (grid cells with a square in Fig. 1). The horizontal distances from the SP to the four grid cells are computed and their z-coordinates are obtained. The SP z-coordinate is then obtained based on the inverse distance to each adjacent grid cell and their respective elevation values (Eq. 1). Ni

j =1

SPZi = å ( dj-1 × z j ) / å dj-1

Fig. 1 Estimating ground elevation on a given point (dot) using the interpolation method based on four grid cells including the grid cell containing the point (grid cell with a cross) and three adjacent grid cells (grid cells with squares) Slika 1. Procjena visine terena odre|enoga poloàja (to~ka) primjenom metode interpolacije zasnovane na ~etirima podacima pravilne mreè to~aka (polje s kriì}em) i na trima susjednim poljima (polja s kvadrati}em) incide with a grid cell center, an interpolation method is used to estimate the SP z-coordinate. The interpolation method uses inverse distance-weighted based on its four adjacent grid cells. For a given SP, (dot in Fig. 1) the model identifies the grid cell containing it (grid cell with a cross in

"j Î N i

(1)

where, SPZi is the z-coordinate of the ith SP, dj is the horizontal distance from the jth grid cell to SP, zj is the z-coordinate of the jth grid cell, and Ni indicates the set of four closest grid cells to the ith SP. Once the three-dimensional coordinates of all SP are determined, the model locates a curve for each intersection point and identifies the position of the beginning and end of curve.

2.2 Locating horizontal curves – Odre|ivanje glavnih to~aka horizontalnoga kru`noga luka We assumed all SP (n) along a proposed road except BOP and end-of-project (EOP) become intersection points (PI in Fig. 2), where curves are located to avoid sharp turns. Each horizontal curve location is determined based on the x- and y-coordinates of the SPi, (same as the PI), SPi-1 and SPi+1, and a user defined minimum allowable radius of the curve (R). In the United States, R ranges from 18 m to 40 m

Fig. 2 An example of horizontal curve design and nomenclature Slika 2. Primjer oblikovanja i osnovne sastavnice horizontalnoga kru`noga luka Croat. j. for. eng. 33(2012)1

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depending on the road standard (Akay 2003). Fig. 2 shows the nomenclature used in the model to determine the location of the beginning and end of the curve (PC and PT, respectively), and the location of the curve center (CC in Fig. 2), whose arc passes through PC, and PT is also determined for posterior calculations of the curve design. For each PI, represented by SPi, the model calculates the direction of the two tangent lines in a two-dimensional (x, y) Cartesian coordinate system as follows: m1 =

m2 =

diff _ y 1 diff _ x 1 diff _ y 2 diff _ x 2

yi - yi-1 xi - xi-1 yi+ 1 - yi xi+ 1 - xi

(2)

PCX = PIX ±

where, Azim and m are azimuth and direction of a tangent line, respectively. Then, the central angle (D in Fig. 2) is calculated as follows: ì 360- |Azim2 - Azim1 | if |Azim2 - Azim1 |> 180 D=í (5) otherwise î |Azim2 - Azim1 | Once the angle D is obtained, the model calculates the tangent distance (T in Fig. 2) from PI to PC and PT (Eq. 6). (6)

(m12 × T 2 ) /(1 + m12 ) m1

PTY = PIY ± (m22 × T 2 ) /(1 + m22 )

(3)

if diff _ y ³ 0 Ù diff _ x > 0 if diff _ y > 0 Ù diff _ x £ 0 (4) if diff _ y £ 0 Ù diff _ x < 0 if diff _ y < 0 Ù diff _ x ³ 0

T = R × tan(D/2)

PCY = PIY ± (m12 × T 2 ) /(1 + m12 )

PTX = PIX ±

where, m1 and m2 represent the direction of the two tangent lines (one arriving at SPi and one leaving from SPi), and xi and yi represent the x- and y-coordinates of the ith SP, respectively. The model converts tangent line directions into azimuths based on the sign of the numerator and denominator of the direction (Eq. 4). ì 90 - tan-1 (m) ï -1 ï 270 + tan (m) Azim = í -1 ï 270 - tan (m) ïî 90 + tan-1 (m)

Using m1, m2, and T, the model calculates the two-dimensional coordinates of PC and PT (Eqs. 7–8 and 9–10, respectively) of the curve associated with SPi by adding or subtracting a difference in the x- and y-coordinates from the coordinates of the PI (Eqs. 7–10).

(m22 × T 2 ) /(1 + m22 ) m2

(7) (8) (9) (10)

These x- and y-coordinates and the slopes m1 and m2 are then used to determine the coordinates at the center of the circle (CC in Fig. 2) as follows: CCX = CCX =

PC Y - PTY + (PC X /m1 ) - ( PTX /m2 ) m1-1 - m2-1 PC Y - PTY + (PC X /m1 ) - ( PTX /m2 ) m1-1 - m2-1

(11) (12)

Once the two-dimensional coordinates of PC, PT, and CC for each of the n-2 curves have been determined, the model estimates the elevation (z-coordinate) of each of these points as described in the previous section.

2.3 Calculating road segment distance – Izra~un staciona`e The road layout has n station points and thus n-1 straight road segments connecting consecutive station points. As one curved road segment is added for each of n-2 intersection points, the total number of road segments (curved and straight segments) becomes 2n-3. Starting from BOP and ending at EOP, these segments alternate between straight and curved segments.

Fig. 3 Plan view of a proposed road including straight and curved road segments Slika 3. Polo`ajni nacrt predlo`ene {umske ceste s prikazom ravnih dionica i dionica u kru`nim krivinama 128

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ì (BOP - PC ) 2 + (BOPY - PC Y (j + 1) ) 2 X X (j + 1) ï ï SDj = í ( PTX (j - 1) - PC X (j + 1) ) 2 + ( PTY (j - 1) - PC Y (j + 1) ) 2 ï 2 2 ïî ( PTX (j - 1) - EOPX ) + ( PTY (j - 1) - EOPY )

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" j Î Q = {1} "j Î Q = {3, 5, 7, ... , ( 2n - 5)}

(13)

"j Î Q = {2n - 3}

where, SDj is the horizontal distance of the jth road segment along the road centerline, and PTX(j–1), PTY(j–1), PTX(j+1), and PTY(j+1) are the x- and y-coordinates of the PT from the (j-1)th segment and the PC from the (j+1)th segment, respectively (Fig. 3). For straight segments, the model calculates the horizontal distance using the x- and y-coordinates of the previous curve PT and the following curve PC (Eq. 13). For the case of the first segment, the distance is calculated from BOP until the first curve PC, and the distance of the last segment is calculated from the last curve PT to EOP (Eq. 13, Fig. 3). For the case of curved segments, the model calculates the segment distance as follows: SDj = 2 × p × R ×

Dj 360

"j Î Q = {2, 4, 6, ... , ( 2n - 4)}

(14)

where, SDj and Dj indicate the horizontal distance along the road centerline and the deflection of tangents in degrees associated with the jth curved segment, respectively (Fig. 3).

2.4 Locating cross-sections for each road segment – Odre|ivanje popre~noga presjeka u svakom profilu ceste The model determines the number of cross-sections (CSN) for a given road segment based on the segment distance and a user-defined cross-section spacing (CSS). CSN for the jth road segment is then calculated by dividing SDj by CSS (Eq. 15). CSNj =

SDj CSS

, as a fractional notation

ì b > 0 Þ CSNj = a + 2 b CSNj = a if í c î b = 0 Þ CSNj = a + 1

(15)

where, CSNj is the number of cross-sections on the jth road segment, a indicates the integer part of CSNj, b and c represent the numerator and denominator of the fractional part, respectively. When the horizontal distance of a road segment is shorter than CSS (SDj< CSS, thus a = 0), two cross-sections are located, one at the beginning and the other at the end of the road segment. All cross-sections along a road segment are located perpendicular to the road centerline. For the given jth road segment, the first cross-section is always located at the beginning of the road segment, the folCroat. j. for. eng. 33(2012)1

lowing cross-sections are spaced successively with an interval of CSS, and the last cross-section is always located at the end of the segment.

2.5 Designing cross-sections – Kreiranje popre~nih presjeka For the purpose of comparing earthwork volumes estimated using different cross-section spacing, we simplified the cross-section design and made the following four assumptions: i) zero-line (balance point) is always located at half of the road width (RW), ii) road surface is flat, iii) road does not include a ditch, and iv) cut and fill slopes are constant. Fig. 4a presents the cross-section design considered in our model. For a given cross-section, horizontal distances from the road center (P1 in Fig. 4b) to its edges (P2 and P3 in Fig. 4b) are assumed to be fixed at RW/2. However, horizontal distances from P1 to the points where cut and fill slopes intersect with the ground profile (P4 and P5 in Fig. 4b) are variable because they depend on the ground slope. To obtain the design points necessary to draw a cross-section, the model first identifies the x-and y-coordinates of points P2 and P3 using the road width, the coordinates of P1, and the direction of the road segment mrs (Fig. 4b). The direction (mrs) is calculated differently for straight and curved segments (Eq. 16 and 17, respectively). ì PC Y (j + 1) - P1 Y "j Î Q = {1, 3, 5, ... , ( 2n - 5)} ï ï PC X (j + 1) - P1 X (16) mrs = í ï EOPY - P1 Y "j Î Q = {2n - 3} ïî EOP - P1 X X -1

æ CC Yj - P1 Y ö ÷ "j Î Q = 2, 4, 6, ... , ( 2n - 4) mrs = – ç { } ç CC Xj - P1 X ÷ ø è (17) where, CCXj and CCYj represent the x- and y-coordinates of CC associated with the jth curved road segment. The location of P2 and P3 are then calculated by adding or subtracting a difference in the x- and y-coordinates from the coordinates of the P1 (Eqs. 18–19).

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Fig. 4 Cross-section design considered by the model (a), and road segment slopes (mrs) used to identify the location of cross-section design points on straight and curved road segments (b) Slika 4. Kreiranje popre~nog profila odre|enog modelom (a), te uzdu`ni nagib dionice {umske ceste (mrs) kori{ten za odre|ivanje osnovnih sastavnica popre~nog profila na ravnim dionicama te u horizontalnim kru`nim krivinama (b)

PY = P1Y ±

( RW / 2) 2 2 rs

m +1

PX = P1X + mrs × (P1Y–PY)

(18) (19)

where, the two pairs of and represent the locations of P2 and P3. To identify the locations of P4 and P5, the model iteratively places two points (Pt1 and Pt2 in Fig. 5) along the cross-section at a fixed distance interval, which is called span-distance (SpD) in our model. At iteration one, Pt1 starts at the edge of the road (P2 or P3 for the left or right side of the road, respectively), and Pt2 starts at meters away from Pt1 (Fig. 5). Thereafter, both points Pt1 and Pt2 are moved farther away from the road edge by SpD meters at each successive iteration. At a given iteration, the model calculates the x-, y-, and z-coordinates of Pt1 and Pt2 using the horizontal distances of Pt1 and Pt2 from P1. The model then checks whether the line formed between Pt1 and Pt2 intersects with the fill or cut slope line. The iteration process stops when the two lines intersect. Once this intersection point is known, the model calculates the horizontal distances (X_dist) from the road edge to P4 and P5 (Fig. 5). The model then calculates the two-dimensional coordinates of points P4 and P5 using Equations 18 and 19 replacing (RW/2) with (RW/2 + X_dist).

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2.6 Calculating cut and fill areas – Izra~un povr{ine iskopa i nasipa To obtain ground elevations along a road cross-section, the model establishes ground points along the cross-section with an interval of SpD meters (Fig. 6a), and then estimates ground elevation on each point using the DEM and the interpolation method described in Section 2.1. The model then calculates cross-section areas (cut and fill) using a well-known

Fig. 5 Iterative process performed by the model to identify the intersection point (P5) between the cut slope and ground surface Slika 5. Postupak ponavljanja rada modela pri identificiranju to~ke sjeci{ta (P5) pokosa iskopa i terena Croat. j. for. eng. 33(2012)1

Improving Accuracy in Earthwork Volume Estimation for Proposed Forest Roads ... (125–142)

æ CSS × TCA R ç ç TCA + TFA R R CVk = è 2 æ CSS × TCA R ç CSS ç TCA R + TFA R FVk = è 2

æ CSS × TCA L ö ÷ × TCA R ç ÷ ç TCA + TFA L L ø +è 2

ö ÷ × TCA L ÷ ø

æ ö CSS × TCA L ÷ × TFA R ç CSS ç ÷ TCA L + TFA L ø +è 2

ö ÷ × TFA L ÷ ø

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(21)

(22)

where, CVk and FVk are the cut and fill volumes of the kth road section defined by two consecutive cross-sections. formula (Eq. 20), which provides the area of a polygon based on the coordinates of its vertices. This formula is derived from one half of the absolute value of the determinant of the matrix formed by the two-dimensional coordinates of the polygon vertices (Hush 1963). TPN

A = 0.5 × å [( xx p × z p + 1 ) - ( xx p + 1 × z p ) ]

(20)

p =1

where, xxp is the horizontal distance from P1 to the pth point in the cross-section, zp is the elevation of the pth point, and TPN is the total number of points representing one side of the road from P1 where the area is calculated. Equation 20 provides cut or fill areas depending on whether all ground elevation

points are above or below the road surface. When both cut and fill areas are on one side of the road in the cross-section, where some ground elevation points are above the road surface and other points are below the road surface (Fig. 6b), the polygons representing either cut or fill are identified and their areas are calculated separately. Areas of the same type (cut or fill) are then added together to compute the total cut and fill areas for the right and left side of the road (TCAR, TFAR, TCAL, and TFAL respectively).

2.7 Estimating cut and fill volumes – Procjena obujma zemljanih radova Based on our assumption that road centerlines are located at the ground level, earthwork volumes

Fig. 6 Cross-section design points used to calculate cut and fill areas (a), and an example of a cross-section having both fill and cut areas on one side of the road center line (P1) (b) Slika 6. Osnovne to~ke popre~noga profila kori{tene za izra~un povr{ina iskopa i nasipa (a) te primjer kada se s iste strane popre~noga profila nalaze povr{ine iskopa i nasipa (P1) (b) Croat. j. for. eng. 33(2012)1

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Fig. 7 Cross sections taken from straight and curved road segments for earthwork volume estimation Slika 7. Popre~ni presjeci na ravnim dionicama te u horizontalnim kru`nim lukovima ceste kao podloga za procjenu volumena zemljanih radova were estimated separately for each side of the road. For straight road segments we used the modified average end-area method developed by Epps and Corey (1990) to estimate earthwork volumes using the cut and fill areas of consecutive cross-sections (Eqs. 21–22) The CSS is the same on both sides of the road center line for straight road segments, whereas this is not the case for curved road segments (Fig. 7). For curved road segments, the model computes the actual cross-section spacing for each side of the road center line (CSSR and CSSL) separately by calculating the arc length of a curve whose radius makes the areas on both sides of the curve equal (A1R= A2R and A1L= A2L in Fig. 7). The arc lengths can be calculated as follows: 2

R + (R ± RW /2) æ CSS × 360 × çç 2 R è

"j Î Q = {2, 4, 5, ... , ( 2n - 4)}

ö ÷ ÷ ø

CSN - 1

(24)

(25)

å CV k =1

FVj =

CSN - 1

å FV k =1

Lastly, the total earthwork of the entire forest road is calculated by adding the total cut and fill volumes estimated for each road segment (Eqs. 26 and 27). TCV =

2 n-3

(26)

(27)

å CV j =1

TFV =

2 n-3

å FV j =1

where, TCV and TFV represent the total cut and fill volumes of the entire road, respectively.

3. Model applications – Primjena modela (23)

where, the two values of D represent CSSR and CSSL. Once cross-section spacings along a curved road segment are obtained for both sides of the road center line, Equations 21 and 22 are used to estimate cut and fill volumes between consecutive cross-sections for curved road segments after CSS in the equation is replaced with CSSR and CSSL. Then, the total cut and fill volumes are calculated for the jth road segment using the following equations:

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CVj =

3.1 Verification – Provjera We created a hypothetical forest road to verify the results of our model and analyze the effects of using a high resolution DEM on earthwork volume estimates. We compared these estimates with those from the traditional method, which considers ground information only from pre-defined station points. The hypothetical road has three station points (Fig. 8a), resulting in two straight and one curved road segments (Fig. 8b). The hypothetical road was laid out Croat. j. for. eng. 33(2012)1

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Fig. 8 Hypothetical forest road layout; a) station point locations, and b) road segment locations Slika 8. Poloàjni nacrt hipotetske {umske ceste; a) poloàj to~aka terenske izmjere, b) poloàj dionica {umske ceste in the southern portion of the Mica Creek watershed located about 67 km southeast of Coeur d’Alene, Idaho, United States, where a LiDAR-derived, 1-meter resolution DEM is available. The road was manually digitized »on-screen« in ArcMap 9.2 based on a 2-meter contour lines layer derived from the DEM of the area. The ground slope in the area was moderate, ranging between 30 and 60%. We considered the following cross-section design and spacing parameters; cut slope (CS) = 1:1, fill slope (FS) = 1.5:1, road width (RW) = 4 m, radius of curve (R) = 20 m, and SpD = 1 m.

3.2 Test case studies – Testiranje studije slu~aja To analyze the effects of various cross-section spacing on the accuracy of earthwork volume estiCroat. j. for. eng. 33(2012)1

mation, we created the layout of three hypothetical 1 km forest roads. These roads were located in areas with slopes between 0–30%, 30–60%, and 60–90% in the southern portion of the Mica Creek watershed to also examine the effects of ground steepness on earthwork volume estimation. We arbitrarily referred to these three areas with increasing slope as low, moderate, and steep terrain areas. The roads were manually digitized »on-screen« in ArcMap 9.2 based on 2-meter contour lines derived from the 1-meter resolution DEM of the area. The allowable road grade used the range from -15% to 15%. We assumed that 1-meter spacing provided the most accurate estimate, and used the earthwork volume obtained from 1-meter cross-section spacing as the true volume in comparison with other spacing. Fig. 9 illustrates the layout

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Fig. 9 Layout of the three hypothetical 1 km forest roads located in low (a), moderate (b), and steep (c) slope areas Slika 9. Prikaz tri hipotetske {umske ceste projektirane na razli~itim kategorijama nagiba terena (a – 0 do 30 %, b – 30 do 60 % i c – 60 do 90 %) of the low, moderate and steep slope forest roads, which have 37, 36, and 37 station points, respectively. We also investigated the effect of terrain ruggedness on earthwork volume estimations. Most of the existing terrain ruggedness indexes calculated from ground elevation and aspect are designed to mea-

sure terrain heterogeneity for large areas using typically a 30 meter raster resolution (Riley et al. 1999, Sappington et al. 2007). When using a high-resolution 1-meter DEM, these indexes are not able to meaningfully capture terrain ruggedness for characterizing terrain variability along road segments. Therefore, we computed the coefficient of variation of the fill

Fig. 10 Number and location of cross-sections along a given straight road segment for different cross-section spacings (1, 2, 4, 8, and 16 meters) Slika 10. Broj i polo`aj popre~nih profila uzdu` ravne dionice {umske ceste za razli~ite ina~ice razmaka izme|u popre~nih profila (1, 2, 4, 8 i 16 metara) 134

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Fig. 11 Cross-section diagrams obtained for the 3-SP hypothetical forest road Slika 11. Crtani popre~ni profil u to~kama terenske izmjere na hipotetskim {umskim cestama and cut areas from all cross-sections in a given road segment, and used this coefficient of variation as a measure of terrain ruggedness in our study (e.g., the higher coefficient represents the more rugged terrain.) The coefficient was computed for all road segments included in the three hypothetical forest roads. Then, the road segments were grouped in three ranges of coefficient of variation: low (<20%), medium (20–40%), and high (³40%). The same parameter values used in the model verification regarding road design (RW and R), cross-section design (FS and CS), and spacing (SpD) were used for these applications. To make comparisons valid, specific cross-section spacings (e.g., 1, 2, 4, 8, 16 meters) were selected so that the same cross-sections can be used for smaller spacings analyzed (Fig. 10). Croat. j. for. eng. 33(2012)1

4. Results and Discussion – Rezultati i rasprava 4.1 Model verification – Provjera modela Using the values of road design parameters specified above, we calculated cut and fill areas of each four cross-sections along the hypothetical forest road layout formed by two straight and one curve segment (see Fig. 8). Cut and fill areas for these cross-sections were also calculated manually to verify our model results (Fig. 11). Table 1 shows the coordinates of all cross-section design points as well as other points along the ground profile for each cross-section shown in Fig. 11. The results of area calculations from the model perfectly matched those calculated manually.

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Table 1 X- and Z-coordinates calculated by the model to draw the cross-sections shown in Fig. 11 Tablica 1. Modelom izra~unate koordinate X i Z nacrtane na popre~nim profilima prikazanim na slici 11 BOP coordinates Koordinata po~etka ceste X1 Z2 –3.6234 1219.8796 –3.0000 1220.1448 –2.0000 1220.9619 –2.0000 1220.3194 –1.0000 1220.6205 0.0000 1220.9619 1.0000 1221.3924 2.0000 1220.9619 2.0000 1221.8531 3.0000 1222.1539 3.3107 1222.2726

PC2 coordinates Koordinata po~etka kru`noga luka 2 X1 Z2 –4.3041 1219.1348 –4.0000 1219.2062 –3.0000 1219.5960 –2.0000 1220.6709 –2.0000 1219.8930 –1.0000 1220.3587 0.0000 1220.6709 1.0000 1221.1097 2.0000 1220.6709 2.0000 1221.7045 3.0000 1222.3679 4.0000 1222.8951 4.3946 1223.0655

PT2 coordinates Koordinata zavr{etka kru`noga luka 2 X1 Z2 –3.3858 1220.2944 –3.0000 1220.3676 –2.0000 1221.2183 –2.0000 1220.6660 –1.0000 1220.9959 0.0000 1221.2183 1.0000 1221.4677 2.0000 1221.2183 2.0000 1221.7801 2.7864 1222.0046

EOP coordinates Koordinata zavr{etka ceste X1 Z2 –4.3221 1219.0900 –4.0000 1219.1963 –3.0000 1219.6519 –2.0000 1220.6380 –2.0000 1220.0318 –1.0000 1220.3419 0.0000 1220.6380 1.0000 1221.0162 2.0000 1220.6380 2.0000 1221.4700 3.0000 1221.7593 3.1738 1221.8119

X-coordinate represents the horizontal distance in meters from P1 located at the origin of x-axis – koordinata X predstavlja horizontalnu udaljenost u metrima od sredi{nje osi ceste (apscisa slike 11) Z-coordinate represents elevation in meters – koordinata Z predstavlja nadmorsku visinu u metrima

Table 2 Comparisons of cut and fill volumes estimated by the traditional method and the model Tablica 2. Usporedba procijenjenoga obujma zemljanih radova standardnom metodom i modelom Distance Udaljenost

Road gradient Nagib ceste

21.84

25.16

26.72

Totals – Ukupno

73.72

–1.33 2.18 –2.17 –

Segment Nº Br. segmenta

Traditional method – Stand. metoda Cut Volume Obujam iskopa

Fill Volume Obujam nasipa

Model – Model Cut Volume Obujam iskopa

Fill Volume Obujam nasipa

Difference – Razlika Cut Volume Obujam iskopa

m3 41.1984 38.7107 27.1596 107.0687

29.3726 31.2789 29.3404 89.9919

Fill Volume Obujam nasipa

%1 31.0145 21.9750 28.8780 81.8676

28.4278 25.0955 35.0607 88.5840

32.84 76.16 –5.95 30.78

3.32 24.64 –16.32 1.59

[(Traditional method – Model) / Model] * 100

Cut and fill volumes were estimated by our model using cross-sections placed every 1 meter. For the traditional method, we only considered the cross-sections located at the beginning and end of each road segment. Volume estimates varied widely between both methods (our model and the traditional method) for the three road segments, ranging from –6% to 76%, but the circular road segment presented the largest differences (Table 2). Cut and fill volumes were overestimated by the traditional method for road segments 1 and 2 (from 3 to 76%), and underestimated for the last road segment (from 6 to 16%). All in all, the traditional method overestimated the total cut and fill volumes for the 3-segment hypothetical forest road by 30% and 2%, respectively, when compared with the results of the model.

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Considerable variability in the cut and fill areas along the three road segments indicated that ground slopes along the road vary significantly (Fig. 12). This terrain variability caused the large differences in earthwork volume estimates between the two methods. While our model (by using 1-meter cross-section spacing) is able to capture details in terrain variations, these terrain details are ignored when only few cross-sections are considered in the traditional method. We also calculated the average value of the end areas resulted from the model and compared it with that from the traditional method (Fig. 12). The differences between the model average and the traditional method have a similar relationship as shown in the earthwork volume estimates presented in Table 2. This also suggests that the differences in earthCroat. j. for. eng. 33(2012)1

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Fig. 12 Cut and fill areas for the 3-SP hypothetical forest road calculated by the model and the traditional method Slika 12. Povr{ine iskopa i nasipa u to~kama terenske izmjere na hipotetskim {umskim cestama izra~unate modelom i standardnom metodom terenske izmjere Croat. j. for. eng. 33(2012)1

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Fig. 13 Cut and fill volumes estimated by the model for the three hypothetical 1 km forest roads at different cross-section spacings Slika 13. Modelna procjena obujma iskopa i nasipa za tri hipotetske {umske ceste duljine po 1 km i za razli~ite razmake izme|u mjerenih popre~nih profila 138

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work volumes between the two methods are caused by their different level of abilities to capture terrain variations. Due to the limitation in obtaining the »true« earthwork volume for a given road segment, it is impossible to properly verify our model for its earthwork volume estimation. However, our comparisons between the model results and the manual calculations of cut and fill area confirm that our model calculates correctly the earthwork volume and provides accurate estimates based on the assumption that the high resolution LiDAR-derived DEM provides an accurate representation of the ground surface.

4.2 Test case studies – Testiranje studija slu~aja The model results of earthwork estimation for different cross-section spacings on the three hypothetical 1000-meter roads are presented and compared with the traditional method in Figure 13. A trend line was added to the estimated earthwork volumes from our model to show the pattern of changes in volume across different cross-section spacings. For the low slope hypothetical road, the traditional method (labeled as »Tra« in Fig. 13) overestimated both cut and fill volumes by 5.0% and 5.9%, respectively, compared with the results of the model with 1-meter cross-section spacing. For the moderate slope road, the traditional method underestimated cut volume by 1.7% but overestimated fill volume by 1.9%. In contrast, the traditional method overestimated cut volume by 2.2% but underestimated fill volume by 12.3% for the road located on steep terrain. The model results from different spacings show a general pattern indicating that as cross-section spacing increases, the earthwork volume estimates become closer to the volumes estimated by the traditional method. This is likely explained by the fact that, as cross-section spacing increases, the ability to capture terrain variations that may exist between consecutive cross-sections decreases, making the volume estimates become closer to those of the traditional method. Although the trend lines may suggest a relationship between the results of our model and the traditional method, no evidence of consistency in over- or underestimation of earthwork volumes was found. Cut and fill volumes were either overestimated or underestimated depending on the specific terrain conditions of road segments. Although Aruga et al. (2005) did not consider the same factors we did in this study, both studies realized that distance between cross-stations is important for accurately estimating earthwork volume. The shorter the distance, the larger ability we have in describing ground variability along the road lay out. Thus, it may be possible to estimate earthwork voluCroat. j. for. eng. 33(2012)1

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me more accurately with short distances between cross-sections. The results of earthwork estimation for the three ranges of terrain ruggedness are presented in Fig. 14. The number of road segments included in each terrain ruggedness class (coefficient of variation) is different. Therefore, to compare the three terrain ruggedness classes, we plotted the average cut and fill volume per linear meter of road for each cross-section spacing used by the model and the traditional method. As expected, the model results of cut and fill volume estimation were similar to the results of the traditional method on the road segments that have a low coefficient of variation. For road segments that are in the medium class of coefficient of variation, the difference in cut volume estimates between the model and the traditional method was minor, but fill volumes estimated by the traditional method were 13% lower than the model results with 1-meter cross section spacing. Lastly, for the road segments with high coefficient of variation (highly rugged terrain), the traditional method overestimated cut volumes by 10.4%, while it underestimated fill volumes by 20.9%. In general, it is noticed that the differences in earthwork volume estimates between our model and the traditional method become larger as terrain ruggedness increases. Previous studies conducted by Aruga et al. (2005) and Akay (2003) also highlighted the importance of short distances between cross-sections in improving the accuracy of earthwork volume calculation, which is consistent with our findings in this study. The more rugged is the terrain where a forest road is laid out, the more important it would be to set out cross-sections in short distances in order to obtain an accurate estimation of earthwork volume. We recognize, however, that surveying a large number of cross-sections in the field might be a time-consuming task. We hope that the use of our model coupled with a high-resolution DEM can help improve the accuracy in earthwork volume estimation without much additional field work.

5. Conclusions – Zaklju~ci In this study, we developed a computerized model to accurately estimate earthwork volumes of low-volume forest roads using a high-resolution DEM, and analyzed the effects of cross-section spacing on the accuracy of earthwork volume estimates. Although the accuracy of earthwork is expected to increase as cross-section spacing is reduced, to our knowledge, our model is the first attempt to quantify the differences between methods using ground information only at station points (the average meth-

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Fig. 14 Cut and fill volumes estimated by the model for the road segments classified into three terrain ruggedness classes across different cross-section spacings Slika 14. Modelna procjena obujma iskopa i nasipa dionica {umske ceste razdijeljenih u tri kategorije neujedna~enosti terena za razli~ite razmake izme|u mjerenih (procijenjenih) popre~nih profila 140

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od) and using high resolution DEM. When ignored, large terrain variations along road segments, as evidenced by the calculations of cut and fill areas from cross-sections spaced every 1meter, resulted in significant earthwork estimation errors. Our model offers a tool to help forest engineers to rapidly assess alternative forest road layouts and assist with planning activities to ensure the economic efficiency of forest road construction. The model verification and application results correspond with previous studies (Kim and Schonfeld 2001, Aruga et al. 2005) in terms of the relationship between accuracy and cross-section spacing. Assuming that 1-meter cross-section spacing provides the »true« earthwork volumes, the accuracy of earthwork volume estimates decreases with the increase of cross-section spacing. Moreover, the discrepancies in earthwork volume estimates between our model and the traditional end-area method become larger in more rugged terrain. Consequently, short cross-section spacing should be used to capture terrain variations and estimate earthwork volume more accurately when forest roads are planned and located on mountainous and rugged terrain. Several assumptions regarding cross-section design were made to simplify the estimation of areas and volumes as described in the method section. Although such assumptions may not seem practical, they do not affect our purpose of comparing earthwork volumes estimated at different cross-section spacings. In addition, the model can be further improved to consider real-world forest road survey and design practices.

6. References – Literatura Akay, A., 2003: Minimizing total cost of construction, maintenance, and transportation costs with computer-aided forest road design. PhD dissertation in Forest Engineering. Oregon State University. 229p. Aruga, K., Sessions, J., Akay, A. E., 2005: Application of an airborne laser scanner to forest road design with accurate earthwork volumes. Journal of Forest Research 10: 113–123.

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Coulter, E. D., Chung, W., Akay, A. E., Sessions, J., 2001: Forest road earthwork calculations for linear road segments using a high resolution digital terrain model generated from LiDAR data. In: Proceedings of the first precision forestry symposium. University of Washington, College of Forest Resources. Seattle, Washington, USA. June 17–20, 2001, 125–129. Easa, S. M., 1992a: Modified prismoidal method for nonlinear ground profiles. Surveying and Land Information Systems 52(1): 13–19. Easa, S. M., 1992b: Estimating earthwork volumes of curved roadways: Mathematical model. Journal of Transportation Engineering 118: 834–849. Epps, J. W., Corey, M. W., 1990: Cut and fill calculations by modified average-end-area-method. Journal of Transportation Engineering 116(5): 683–689. Hickerson, T. F., 1964: Route location and design. New York, McGraw-Hill, 5th edition Hush, B., 1963: Forest mensuration and statistics. Ronald Press Co, New York. 474p. Kim, E., Schonfeld, P., 2001: Estimating highway earthwork cross sections by using vector and parametric representation. Transportation Research Record 1772: 48–54. Paper No 01-2682 Reutebuch, S. E., McGaughey, R. J., Andersen, H., Carson, W. W., 2003: Accuracy of a high-resolution digital terrain modelunder a conifer forest canopy. Canadian Journal of Remote Sensing 29(5): 527–535. Riley, S. J., DeGloria, S. D., Elliot, R., 1999: A terrain ruggedness index that quantifies topographic heterogeneity. International Journal of Science 5: 1–4. Sappington, J. M., Longshore, K. M., Thompson, D. B., 2007: Quantifying landscape ruggedness for animal habitat analysis: A case study using bighorn sheep in the Mojave desert. The Journal of Wildlife Management 71(5): 1419–1426. Stückelberger, J., Heinimann, H., Burlet, E., 2006: Modeling spatial variability in the life-cycle costs of low-volume forest roads. European Journal of Forest Research 125(4): 377–390.

Sa`etak

Pobolj{anje to~nosti procjene zemljanih radova za predlo`ene {umske ceste primjenom digitalnoga modela terena visoke rezolucije Zemljani su radovi (radovi na donjem ustroju) najve}i tro{ak pri izgradnji {umskih cesta maloga prometnoga optere}enja i ~ine oko 80 posto ukupnih tro{kova izgradnje. To~nost procjene obujma zemljanih radova prijeko je potrebna pri procjeni tro{kova izgradnje {umskih cesta, racionalizaciji i kontroli tro{kovne sastavnice te pri

Croat. j. for. eng. 33(2012)1

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izgradnji i uspostavi ekonomski u~inkovite primarne {umske prometne infrastrukture. Koli~ina se zemljanih radova kod {umskih cesta uobi~ajeno temelji na procjeni podataka dobivenih terenskom izmjerom na trasi {umske ceste. Povr{ina popre~nih profila procjenjuje se u svakoj to~ki izmjere, a zatim se klasi~ne metode, kao {to su metoda prosje~nih povr{ina ili metoda prizme, primjenjuju za izra~un obujma zemljanih radova izme|u susjednih popre~nih profila. Navedene metode pretpostavljaju jednoli~an teren izme|u popre~nih profila, {to pri kona~noj procjeni rezultira nedovoljno to~nim podacima u brdskim i planinskim podru~jima. U ovom je istraìvanju razvijen ra~unalni model pobolj{ane to~nosti procjene zemljanih radova na {umskim cestama primjenom visoko razlu~iva digitalnoga modela terena. Istraìvan je utjecaj udaljenosti izme|u profila na to~nost procjene obujma zemljanih radova primjenom predloènoga ra~unalnoga modela. Istraìvane se {umske ceste nalaze u razli~itim reljefnim podru~jima, a prikazane su specifi~nim terenskim ~imbenicima te procjenom koli~ine zemljanih radova za razli~ite razmake izme|u profila. Analiziran je utjecaj razmaka izme|u popre~nih profila na to~nost procjene koli~ine zemljanih radova. Nadalje, utvr|ena je varijabilnost povr{ina popre~nih profila koja je kori{tena kao mjera nejednolikosti terena te su istraèni i u~inci spomenute varijabilnosti na to~nost procjene obujma zemljanih radova. Izra|eni je ra~unalni model primijenjen na trima hipotetskim {umskim cestama na terenima nagiba <30 %, 30–60 % i 60–90 %, a procjena obujma zemljanih radova dobivenih modelom uspore|ena je sa standardnom metodom povr{ina u to~kama terenske izmjere. Op}enito gledaju}i, rezultati pokazuju kako pove}anje razmaka izme|u popre~nih profila smanjuje to~nost procjene obujma zemljanih radova zbog nemogu}nosti uzimanja u obzir nejednolikosti terena. Utvr|ene su razlike u procjeni obujma zemljanih radova izme|u predloènoga modela i klasi~nih metoda u rasponu od 2 do 12 % neovisno o nagibu terena. Jasniji je smjer primije}en kada se uspore|uju procjene obujma zemljanih radova predstavljenim ra~unalnim modelom u odnosu na standardne metode. Pove}anje nejednolikosti terena proporcionalno utje~e na razliku uspore|enih metoda u rasponu od 2 % na jednolikim terenima (izraèno niskim koeficijentom varijacije povr{ine profila) pa do 21 % na nejednolikim terenima (izraèno visokim koeficijentom varijacije povr{ine profila). Klju~ne rije~i: {umske ceste, obujam zemljanih radova, projektiranje cesta, LiDAR, digitalni model terena

Authors’ address – Adresa autorâ: Asst. Prof. Marco A. Contreras, PhD. e-mail: marco.contreras@uky.edu University of Kentucky College of Agriculture Department of Forestry KY40546-0073 Lexington Thomas Poe Cooper Building 214 USA

Received (Primljeno): September 15, 2011 Accepted (Prihva}eno): February 21, 2012

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Pablo Aracena, Graduate Research Assistant e-mail: pablo.aracena@umontana.edu Assoc. Prof. Woodam Chung, PhD. e-mail: woodam.chung@umontana.edu University of Montana College of Forestry and Conservation Department of Forest Management MT59812 Missoula USA Croat. j. for. eng. 33(2012)1

Original scientific paper – Izvorni znanstveni rad

Planning Forest Accessibility with a Low Ecological Impact Eugen Iordache, Mihai-Daniel Nita zh , Ioan Clinciu Abstract – Nacrtak This paper examines a new approach to forest accessibility planning based on a GIS road development algorithm and some topographically derived indices. The aim of the paper is to propose and validate a method of assessing forest accessibility introducing an ecological approach, based on morphological impact. For the case study, both cartographic material (DEM) and measured items (existing road network) were used in applying the method. The case study offered the data and possibility to analyze, compare and take into consideration the ecological impact on planning forest accessibility. Keywords: planning, forest accessibility, ecological impact, soil erosion, GIS

1. Introduction – Uvod Romanian forest lands extend over 6.3 million ha, representing 27% of the total area of the country. The distribution of forest lands is such that 90% of it is on terrain classified as hills or mountains. Hence, it follows that the majority of forestry works are carried out on rough topography, where the slopes frequently account for more than 25% of the whole area. Forest accessibility is low due to the lack of adequate access roads. From a total of 6.3 million ha of forest land, only 4.1 million ha could be considered accessible; the rest of these forest lands are not connected to an existing transport system. The road density of the forest road network is 6.2 m/ha (Iordache 2007). At present, the available forest transport system (truck roads, narrow gauge railways, public roads, servicing roads) consists of 39,186 km intended to cover various forest activities. Forestry production always covers considerable areas and from the point of view of natural forest management simple road construction is not sufficient. According to Dietz et al. (1984) and Dürrstein (1998) a proper forest opening has always to be developed in a sequence of stages: Þ connecting the forest to the public transport system (roads, railroads), Þ access to the different parts of the forest, Þ access to the single compartments or units of the forest. Croat. j. for. eng. 33(2012)1

Due to low road density in Romania, planning of forest accessibility remains a main issue in further development of the road network. Taking into consideration ecological principles, like soil erosion, terrain disruption, GIS based algorithms can offer a sustainable ecological planning of forest accessibility (Iordache and Nita 2008). The main ecological impact made by road development can occur by landsliding from road surfaces during plantation harvest and post-harvest periods. It is estimated that 50–90% of sediment in planted forests comes from roads (Fransen et al. 2001). Sediments from roads can have a bigger environmental impact than landslide sediments because of the higher concentrations of fine sediments (Elliot et al. 1993, Fahey and Marden 2000, Hicks and Harmsworth 1989). Sediment may affect water habitats and landscape ecology by affecting the natural flow of the rivers and perturbing geomorphic channel processes by excessive sedimentation. Quantifying possible morphological impact from forest roads represents an important issue both for road planners and for decision makers. This can either be done by implementing potentially expensive erosion control measures after the road network has been established or by designing the forest road network in a way to minimize erosion (Cochrane et al. 2007). This is why the aim of the present study is to propose and validate a method of road network deve-

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lopment that takes into consideration areas with high occurrence of ecological perturbation. The purpose of research is to allow forest road planners to minimize the impact of forest roads on morphometry and consequently on habitats and ecology.

2. Material and Methods – Materijal i metode The research material included an existing road network divided into 11 road segments situated in Lesuntu Mare Upper Watershed (Fig. 1). This watershed is situated in a mountainous area of Carpathian Mountains. The following research materials were used: Þ Cartographic data – DEM extracted from topographic contour lines, having a 5 m cell size (pixel) and 1 m height accuracy (according to topographic plan specifications), Þ Measured data – 11 road segments measured in the field with a handheld GPS (3 m accuracy). The method itself contains the following calculating steps: Þ Preparatory– correcting the DEM by removing sinks and peaks, Þ Accessibility calculation – calculating the accessibility distance from every cell to road network. Accessibility was calculated using cost function GIS based algorithm developed in ArcMap 9.2. From the cell perspective, the objective of the cost functions is to determine the least costly path to reach the

Fig. 1 Location of the studied forest road network Slika 1. Poloàj istraìvane mreè {umskih cesta cell from the least costly source for each cell location in the analysis window. For each cell, determination was made of the least accumulative cost path from a source, the source that allows for the least cost path, and the least cost path itself. The formula used by algorithm to calculate the total cost from one cell to another is: Cost_dist = Surface_dist × Vertical_factor × (Friction × Horizontal_factor) 2

(1)

Fig. 2 Determination of horizontal factors Slika 2. Odre|ivanje horizontalnih faktora 144

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harsh ecological conditions. From this point of view, TRI supports an easy way for determining the areas where a forest road construction can lead to higher ecological impact than in normal conditions. Þ Mapping the zones with the highest ecological risk – The proposed method uses both the cost distance grid and topographic grids for better quantifying the areas where the forest accessibility provides the lowest ecological impact. Þ Tracing the areas for the best placement of the new roads.

3. Results and discussion – Rezultati i rasprava

Fig. 3 Horizontal factor dependence function Slika 3. Funkcija ovisnosti horizontalnoga faktora The horizontal factors determine the difficulty of moving from one cell to another while accounting for the horizontal elements that may affect the movement. To determine the HF for moving from one cell to the next, the prevailing horizontal direction at the processing cell was established from the horizontal direction raster (Fig. 2). A linear function was used as horizontal factor function, (Fig. 3), in order to set the algorithm to stop any distance calculation over the ridges. Data analysis involves four steps: Þ Inaccessible area identification – based on accessibility raster, a threshold was used in order to identify areas situated more than 500 m away from the network. Þ Morpho–Ecological impact assessment – calculating ruggedness index and determining the possible ecological influence of the new road. The topographic ruggedness index (TRI) was developed by Riley et al. (1999) and is used to express the amount of elevation difference between adjacent cells of a digital elevation model. The calculus uses the difference in elevation values of a central cell and the neighboring cells. TRI is then derived and corresponds to average elevation change between any point on a grid and the surrounding area. Habitats and many factors influencing them (micro-climate, humidity, soil layer, etc.) directly correspond to morphometry (slope, aspect, curvature). Higher slopes influence shallow soil layers, lower humidity and therefore Croat. j. for. eng. 33(2012)1

The digital elevation model was used for calculating Lesuntu Mare Upper Watershed forest accessibility (Fig. 4). By setting the distance threshold to up to 1 km to the nearest road, the resulting grid was divided in 2 areas: accessible and inaccessible forested areas (Fig. 5). This first step in the proposed methodology offers a useful geographic distribution of the inacces-

Fig. 4 Aspect used as data input for calculating the forest accessibility Slika 4. Ekspozicija kori{tena kao ulazni podatak za izra~un pristupa~nosti {umi 145

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Fig. 5 Accessible and inaccessible forested zones Slika 5. Pristupa~na i nepristupa~na {umom obrasla podru~ja

cessible: 113B, 127C, 126E, 123C, 123D, 118B, 118D, 118C, 126D, 120A, 119B, 124B, 123B, 125A, 126B, 126F, 127B – in total 262 hectares. Using traditional road planning methods, a possible route was created in order to increase accessibility in these compartments. Using the ruggedness index (Riley et al. 1999), the erosion risk zones were derived in order to identify the zones where higher ecological impact of the roads could be expected (Fig. 6). Knowing these areas, some road sections were marked as highly prone to erosion. In practice two recommendations appeared to fit in this issue: Þ either change the course in order to detour the zones with high ecological impact, Þ either apply an additional cost to those sections in order to compensate the ecological impact if no other solution is possible. The application of the method is simple and requires few input data. The computational time depends directly on the area of digital elevation model, which affects the application of the simulation. Using the above method by adding accessibility to 262 hectares, the results revealed possible additional costs in 4 road segments. This simulation offered additional information not only about the costs that can occur, but also about the specific zones characterized with a high probability of erosion processes.

4. Conclusions – Zaklju~ci

Fig. 6 Mapping the zones with the highest erosion risk Slika 6. Kartiranje podru~ja s najve}im rizikom od erozije sible forested areas, which is a key goal for forest road planners and forest managers. For example taking a compact area and using GIS tools the next compartments were found as inac-

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From the very beginning, planning and building forest roads have severely impacted the ecosystem. The idea of identifying the areas with low ecological impact is not a new one but it cannot be identified in the methods of forest road planning. The complexity of the phenomenon is a special problem. With the above method, the purpose of this paper was to underline that using a GIS application and geospatially referenced data, the path with the lowest ecological impact on the soil and indirectly on the ecosystem can be easily identified. Depending on the accuracy of the data input, the output can either result in a large scale planning (based on SRTM model or other global models), or in a small scale planning and management (based on the model developed with LIDAR techniques or topographical measurements). The output data not only offered the estimation of the potential risk to the zone, but additionally also offered geographic information on the method outcome. Croat. j. for. eng. 33(2012)1

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The proven fact that planning forest accessibility based on low ecological impact can be done based on real and accurate data will be a strong and sustainable argument to support this approach in practice.

transport, June 17–22, 1996, Sinnaia, Romania, FAO Rome, 34–43.

Acknowledgements – Zahvala

Fahey, B.D., Marden, M. 2000: Sediment yields from a forested and a pasture catchment, coastal Hawke’s Bay, North Island, New Zealand. Journal of Hydrology (NZ) 39(1): 49–63.

This paper is supported by the Sectorial Operational Programme Human Resources Development (SOP HRD), financed by the European Social Fund and by the Romanian Government under the Contract No. POSDRU/6/1.5/S/6. We would like to thank the scientific reviewers for suggestions and recommendations made in order to increase the quality of this paper.

5. References – Literatura Cochrane, T. A., Egli, M., Phillips, C., Acharya, G., 2007: Development of a forest road erosion calculation GIS tool for forest road planning and design. International Congress on Modelling and Simulation: Land, Water & Environmental Management: Integrating Systems for Sustainability, Christchurch, New Zealand, December 1–5 2007, 1273–1279. Dietz, P., Knigge, W., Löffler, H., 1984: Walderschließung. Verlag Paul Parey, Hamburg und Berlin, 1–426. Dürrstein, H., 1998: Opening up of a mountainous region – decision-making by integration of the parties concerned applying cost-efficiency analysis. In: Proceedings of the Seminar on environmentally sound forest roads and wood

Elliot, W. J., Foltz, R. B., Luce, C. H., 1993: Validation of the WEPP model for forest roads. In: ASAE International Winter Meeting, December 14–17, 1993, Chicago, IL. ASAE.

Fransen, P. J. B., Phillips, C. J., Fahey, B. D., 2001: Forest road erosion in New Zealand: overview. Earth Surface Processes and Landforms 26(2): 165–174. Hicks, D. M., Harmsworth, G. R., 1989: Changes in Sediment Yield Regime During Logging at Glenbervie Forest, Northland, New Zealand. In: Proceedings of the 1989 Hydrology and Water Resources Symposium, Christchurch, NZ, 424–428. Iordache, E., 2007: Opening up the Romanian forests: Presents and perspectives. In: Proceedings of Austro 2007 – FORMEC’07 »Meeting the Needs of Tomorrows’ Forests: New Developments in Forest Engineering«, October 7–11, 2007, Wien–Heiligenkreuzl, Austria, University of Natural Resources and Applied Life Sciences Viena, CD-ROM. Iordache, E., Nita M., 2008: Using GIS applications in road network development taking into consideration soil erosion. In: Proceedings of 3rd International Scientific Conference »Fortechenvi 2008«, May 26–30, 2008, Prague, Chech Republic, Mendel University of Agriculture and Forestry Brno. Riley, S. J., De Gloria, S. D., Elliot, R., 1999: A terrain ruggedness that quantifies topographic heterogeneity. Intermountain Journal of Science 5(1–4): 23–27. http://webhelp.esri.com (accesed 1st march 2011).

Sa`etak

Planiranje otvaranja {uma na osnovi okoli{ne pogodnosti U ovom se radu istraùje mogu}nost planiranja otvaranja {uma primjenom GIS-a temeljem mreè {umskih cesta te nekih topografskih izvedenih indeksa. Cilj je rada predloìti i potvrditi metodu procjene pristupa~nosti {ume uvo|enjem ekolo{koga pristupa s obzirom na morfolo{ki utjecaj. Za potrebe studije te primijenjene metode kori{teni su kartografski podaci (DEM – digitalni model terena) i izmjereni prostorni podaci (postoje}a cestovna mreà). Studija je ponudila analizu ekolo{koga utjecaja na planiranje pristupa~nosti {uma. Podru~je istraìvanja uklju~ilo je mreù postoje}ih {umskih cesta podijeljenu u 11 cestovnih segmenata smje{tenih na lokaliteta Lesuntu Mare u Karpatima. U istraìvanju su kori{teni: Þ kartografski podaci – digitalni visinski model dobiven iz topografskih slojnica, veli~ine }elije 5 m × 5 m i visinske to~nosti unutar jednoga metra Þ izmjereni podaci – 11 cestovnih odsje~aka (segmenata) izmjerenih na terenu s ru~nim GPS-om (poloàjne to~nosti 3 metra). Sama metoda sadrì ove korake prora~una: Þ pripremni – ispravljanje (korigiranje) digitalnoga visinskoga modela uklanjanjem vrhova i dolova (najve}ih i najmanjih vrijednosti)

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Þ prora~un pristupa~nosti – prora~un pristupne udaljenosti od svake }elije do cestovne mreè kori{tenjem tzv. tro{kovne funkcije (iz grupe funkcija Spatial Analyst ra~unalnoga programa »ESRI Arc GIS 9.2«) Þ procjena morfolo{ko-ekolo{koga utjecaja – prora~un indeksa neujedna~enosti terena i odre|ivanje mogu}ega ekolo{koga utjecaja nove ceste na okoli{ Þ kartiranje podru~ja s najve}im ekolo{kim (erozijskim) rizikom Þ odre|ivanje podru~ja za najbolji prostorni smje{taj novoplaniranih cesta. Za prora~un pristupa~nosti {umi Lesuntu Mare izra|en je digitalni model terena (slika 1). Kao funkcija horizontalnoga faktora kori{tena je linearna funkcija (slika 3) kako bi se odredio algoritam koji zaustavlja svaki daljnji prora~un udaljenosti ako se nai|e na greben (sedlo). Postavljanjem praga udaljenosti do jednoga kilometra od najbliè {umske ceste rezultantni je raster razdijeljen u dva podru~ja: pristupa~nu i nepristupa~nu {umsku povr{inu. Kori{tenjem tradicionalnih metoda planiranja cesta kreirane su mogu}e trase kako bi se pove}ala otvorenost pojedinih {umskih povr{ina (odjela). Koriste}i indeks neujedna~enosti terena (Riley i dr. 1999) izlu~ene su zone rizika od erozije kako bi se identificirala podru~ja u kojima bi okoli{ni utjecaj cesta bio ve}i, a gradnja nepovoljna. Upotrebom metode dodatnoga tro{ka na pojedinim odsje~cima zbog kompenzacije ekolo{koga utjecaja pove}ana je otvorenost na dodatna 262 hektara, a rezultati su ukazali na mogu}e dodatne tro{kove na 4 cestovna odsje~ka. Ova je simulacija ponudila dodatne podatke ne samo o tro{kovima koji se mogu pojaviti ve} i o podru~jima koja su izloèna visokoj vjerojatnosti pojave erozije. Istraìvanje je pokazalo va`nost primjene GIS-a pri analizi geoprostorno referenciranih podataka kojima se jednostavno moè identificirati trasa na kojoj je najmanji ekolo{ki utjecaj na tlo ili posredno na ekosustav. Ovisno o to~nosti te preciznosti unesenih podataka, izlazni se podaci mogu koristiti ili za planiranje velikih razmjera ili za planiranje i upravljanje podru~jima lokalnoga karaktera. Klju~ne rije~i: planiranje, otvaranje {uma, utjecaj na okoli{, erozija tla, GIS

Authors' address – Adresa autorâ:

Received (Primljeno): March 9, 2011 Accepted (Prihva}eno): August 11, 2011

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Asst. Prof. Eugen Iordache, PhD. e-mail: i.eugen@unitbv.ro zh , MSc. Mihai-Daniel Nita e-mail: nita_mihai_daniel@yahoo.com Prof. Ioan Clinciu, PhD. e-mail: torenti@unitbv.ro Faculty of Silviculture and Forest Engineering Transilvania University of Brasov Sirul Bethoven 1 500123 BraÕov ROMANIA Croat. j. for. eng. 33(2012)1

Original scientific paper – Izvorni znanstveni rad

Static Horizontal Positions Determined with a Consumer-Grade GNSS Receiver: One Assessment of the Number of Fixes Necessary Pete Bettinger, Krista Merry Abstract – Nacrtak Over the course of a year, a consumer-grade GNSS receiver was used to collect data in three forest types in northeastern Georgia (USA). During each visit, fifty position fixes were collected to estimate a horizontal position. Since there has been a significant amount of debate regarding the appropriate number of position fixes to collect to determine a position, this analysis was conducted to understand whether the static horizontal position error (a) changed over the collection period of fifty position fixes, (b) was significantly different than a single position fix collected to estimate the positions, and (c) was a function of forest type. We failed to reject the hypothesis that static horizontal position accuracy does not significantly change with increasing numbers of position fixes collected to determine a position, yet we favor rejecting the hypothesis that trends do not differ by forest type or by density of trees per unit area. The results are not entirely conclusive, and the time (season) of year may influence the results observed within certain forest types (e.g., young coniferous forests). We observed a trend that the static horizontal position accuracy in a young coniferous forest, on average, improved from a position determined by a single position fix to a position determined from the average of fifty position fixes. A much less relevant trend in accuracy was observed in a deciduous forest, and no trend at all was observed in an older coniferous forest. Keywords: Global navigation satellite systems, static horizontal position accuracy, root mean squared error, linear regression

1. Introduction – Uvod Satellite navigation and positioning systems (or more commonly, Global navigation satellite systems (GNSS)) utilize electromagnetic energy emitted by earth-orbiting devices (space vehicles, or satellites) to establish positions on earth. The United States (NAVSTAR GPS), the Russian Federation (GLONASS), the European Union (GALILEO), India (IRNSS), and China (COMPASS or B iDou-2) all either have developed, or are developing, GNSS that will provide signals useful in determining positions on earth. Each of these programs broadcasts, or plans to broadcast, signals in various ranges near the L1 (about 1575 MHz) and L2 (about 1228 MHz) band frequencies of the electromagnetic spectrum. GNSS receiver manufacturers are developing (or have developed) techCroat. j. for. eng. 33(2012)1

nology to collect and use the information emitted by the satellites to determine positions on earth, and to facilitate mapping or navigational processes. In practice and in the published literature, GNSS receivers are generally divided into three classes: survey-grade, mapping-grade, and consumer-grade (or recreation-grade). Survey-grade receivers can provide sub-centimeter static horizontal position accuracy in open conditions, and sub-meter accuracy in or near forests (Pirti 2008), yet lengthy signal acquisition times may be required. Mapping-grade receivers may be able to provide sub-meter static horizontal position accuracy in open conditions, but usually 2 – 5 m accuracy in forests. Consumer-grade receivers are the lowest cost of the three classes, and generally provide static horizontal position accuracy in the 5 to 15 m range in forested conditions.

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Augmentation processes are available to increase the quality of data collected by GNSS receivers. These include space-based augmentation systems (e.g., the United States WAAS program, the European Space Agency EGNOS program, the Canadian MSAT program, and others), ground-based augmentation systems (differential GPS or DGPS, and real-time kinematic or RTK processes), and post-process differential correction. Depending on the receiver used and the data the receiver provides, some or all of these augmentation processes may be available. In some cases, particularly with low-cost consumer-grade GNSS receivers, very few augmentation processes may be available. Using GNSS technology in a forested environment presents perhaps one of the most challenging data collection situations, because of the effects of trees on signals (Pirti 2005). The influence of tree canopies on satellite signals is important, as horizontal and vertical accuracy and precision (even with survey-grade receivers) can be affected (Pirti 2008). Even though contemporary GNSS receivers may have advanced satellite tracking technologies, signals are noisier, weaker, and subject to multipath and diffraction when forced to pass through tree canopies (Pirti 2008). Therefore, in forestry, the accuracy of positions determined with GNSS technology is of concern, since manufacturer’s statements of typical data quality do not include a description of the testing environment. GNSS technology is now widely used in forestry and other natural resource fields, and professionals frequently use data collected with these devices for positional and navigational purposes. Some examples of uses include the delineation and identification of forest cutting area boundaries, forest roads, forest trails, inventory plot locations, streams, and wildlife nest locations. The need and desire for highly accurate locational information is understandable since many management decisions are based on data such as these. A number of recent research efforts have evaluated and illustrated the usefulness of GNSS technology in natural resource management (e.g., Andersen et al. 2009, Danskin et al. 2009a, 2009b, Keskín et al. 2009, Wing 2009, Bettinger and Fei 2010, Klimánek 2010, Pirti et al. 2010, Ransom et al. 2010). These and other studies conducted within the last decade provide forest managers with periodic assessments of the positional accuracy of GNSS technology under forested conditions. However, the number of determined horizontal position fixes necessary to obtain the highest level of static horizontal

position accuracy possible under tree canopies is still open to debate. About a decade ago, Sigrist et al. (1999) suggested that numerous (300) static horizontal position fixes were necessary at each point visited, yet others (e.g., Bolstad et al. 2005, Wing and Karsky 2006) have since suggested that the static horizontal position determined from an average of a large set of position fixes may be no better than the position determined from a single position fix. Other research (Wing et al. 2008, Danskin et al. 2009a) has suggested a small set (30 or fewer) of static horizontal position fixes are preferred. Most of these discussions concern consumer-grade or mapping-grade GNSS receivers, since it is well known that survey-grade GNSS receivers need a significant amount position fixes to arrive at very precise and highly accurate positions (Hasegawa and Yoshimura 2003, Yoshimura and Hasegawa 2003, Naesset and Gjevestad 2008, Andersen et al. 2009). The objectives of this work were therefore to understand how static horizontal position accuracy might change with the number of position fixes collected during a visit to a known control point. The hypotheses are: H1: Static horizontal positional accuracy does not significantly change with an increasing number of position fixes used to determine a position’s location. H2: Trends in static horizontal positional accuracy, with an increasing number of position fixes, do not differ based on forest type or tree density. Using data collected over the course of one year (and previously described in Bettinger and Fei 2010), we address these two hypotheses.

2. Materials and Methods – Materijal i metode Between September 2008 and September 2009, data were collected with a Garmin Oregon 300 consumer-grade GPS receiver nearly every day, under a variety of environmental conditions. Static horizontal positions were determined in a young coniferous forest (loblolly pine, Pinus taeda), an older coniferous forest, and a deciduous forest, each located within the Whitehall Forest GPS Test Site1 in Athens, GA. The purpose of this study was to determine whether long-term data collected with a consumer-grade GPS receiver were sensitive to stand type, time of year, and a number of environmental variables. In a previously published study (Bettinger and Fei 2010), we found no significant relationship between observed

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(older hardwood) forest. The deciduous forest is dominated by oak (Quercus spp.) and hickory (Carya spp.). All three control points are located in what we considered upper slope positions for the surrounding area, and therefore represented the best choices for comparison among the three forest types. The three control points were visited once per test day over the course of a year, the order of visit to each point was randomized, and fifty position fixes were collected at each point during each visit. The travel time between each of the three required about three minutes. Our assumption (collecting fifty position fixes at each point during each visit) is consistent with recent studies (Danskin et al. 2009a, 2009b, Wing 2008, Wing et al. 2008), yet is a compromise based on previous research in this area. Although until now

Fig. 1 A map of the three Whitehall Forest GPS Test Site points used in this research Slika 1. Karta pozicijâ pokusa GPS-om u {umi Whitehall koje su se koristile u ovom istra`ivanju static horizontal positional accuracy and several environmental variables (air temperature, relative humidity, atmospheric pressure, and solar wind speed). No significant differences were noted within a forest type as seasons of the year changed. The average static horizontal position accuracy was 11.9 m, 6.6 m, and 7.9 m for the young coniferous, older coniferous, and deciduous forests, respectively (Bettinger and Fei 2010). Three control points (numbers 6, 31, and 37) from those available at the Whitehall Forest GPS Test Site were selected for this research (Fig. 1). Control point 37 is located in the young loblolly pine forest (Fig. 2), and the forest conditions at the time of the study are illustrated in Table 1. Control point 31 is located in the older coniferous forest, and control point 6 is located in the deciduous

Fig. 2 An aerial view of the Whitehall Forest GPS Test Site and the three test points used in this research Slika 2. Zra~ni snimak GPS-om pokusnih pozicija u {umi Whitehall i triju testnih pozicija kori{tenih u ovom istra`ivanju

Table 1 Characteristics of the forests on the Whitehall Forest GPS Test Site (Georgia, USA) where the study was conducted Tablica 1. Zna~ajke {uma na podru~ju Whitehall (Georgia, SAD) ispitivanom GPS-om gdje je provedena studija Characteristic – Zna~ajka Forest age – Dob {ume Basal area – Temeljnica Tree density – Broj stabala Aspect – Polo`aj, inklinacija Slope – Nagib Elevation – Nadmorska visina Canopy closure – Obrast

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Forest type – Tip {ume Young coniferous – Mlada {uma ~etinja~a Older coniferous – Starija {uma ~etinja~a 15 years 60 – 70 years 2 –1 30 m ha 20 m2ha–1 182 ha–1 146 ha–1 Southwest – Jugozapadna South – Ju`na 8% 2% 212 m 222 m 95% 50%

Deciduous – [uma lista~a 60 – 70 years 20 m2ha–1 356 ha–1 Northeast – Sjeveroisto~na 18% 210 m 90%

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the results have not been statistically tested, at the time of data collection we observed a number of patterns in the fifty position fixes collected. These included: (1) static horizontal position accuracy increased as the number of position fixes increased, (2) static horizontal position accuracy decreased as the number of position fixes increased, and (3) static horizontal position accuracy increased, then decreased, or vice versa as the number of position fixes increased. There seemed to be no clear reason for these patterns, and the patterns were not consistent within a forest type on a data collection day. This research was unfunded, therefore the lead author decided that approximately 20 minutes per day could be spared to collect data at the test site. In addition, it was assumed that only one GNSS receiver would be assessed, and that the operating parameters of the receiver would be fixed for the entire duration of the study so that similar data collection conditions would be used. This implied that during each visit to each control point, the consumer-grade receiver was plumbed directly over the control point. The lead author would then stand on the north side of each control point as data was collected. Space-based augmentation of signals would be disabled since the receiver was unable to report the percentage of time the service was available. Finally, position fixes were captured manually, using a 2 – 3 second interval. Static horizontal position data were collected between 10:30 AM and 16:30 PM, and varied according to the daily schedule of the lead researcher. We found it impossible to collect data during a consistent period of time throughout a year, given other responsibilities. That being said, the average Coordinated Universal Time (UTC) for data collection activities in the older coniferous forest was 19:45 in the fall season, 19:40 in the winter season, 18:11 in the spring season, and 17:04 in the summer season (as reported in Bettinger and Fei 2010). The effect of variations on data collection activities on the results is unknown, however trends in data collection times (e.g., consistently collecting data in the morning in the winter season) were not evident. The raw (non-transformed) data representing the root mean squared error (RMSE) of each position fix determined was used in a linear regression analysis to determine the slope and coefficient of determination (R2) of a line that best fits the fifty position fixes of a visit to a control site. This analysis was performed for all 298 days of the study, and each of the three forest types visited during these days. The slope of the regression line should be negative if additional position fixes increase the static horizontal position accuracy, should be positive if additional position

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fixes decrease the static horizontal position accuracy, and will be nearly zero if additional position fixes have no effect on static horizontal position accuracy. In these cases of simple linear regression, the independent variable is the RMSE of each position fix, and the dependent variable is the position fix number (1 to 50). For presentation purposes, we average the slope values and the coefficient of determination values to help determine whether to accept or reject the first hypothesis, that static horizontal positional accuracy would not be significantly different with an increasing number of position fixes used to determine a position’s location. An analysis of these results by season is also performed. For the purpose of this study, the fall season covered the period from September 15, 2008 to December 14, 2008, the winter season covered the period from December 15, 2008 to March 14, 2009, the spring season covered the period from March 15, 2009 to June 14, 2009, and the summer season covered the period from June 15, 2009 to September 15, 2009. Given a full set of fifty position fixes collected during a single visit to a single control point, this data was reduced to six estimates of RMSE: (1) the first position fix, (2) the average of the first ten position fixes, (3) the average of the first twenty position fixes, (4) the average of the first thirty position fixes, (5) the average of the first forty position fixes, (6) the average of all fifty position fixes collected. To be clear, RMSE was determined for each position fix, and the RMSE values were then averaged to arrive at the group average static horizontal error. Since there was a significant amount of variation in RMSE values from one day to the next, the difference between the RMSE of the first position fix and the average RMSE values of the other five groups were used in the analysis. This analysis was designed to address the second hypothesis, which suggested that the results may differ based on forest type or tree density. This analysis was also performed by season to determine whether seasonal variation may explain some of the differences in the data collected.

3. Results – Rezultati The average change in static horizontal position accuracy for positions determined in each of the three forest types, from the first position fix determined to the last (the fiftieth), was negligible, as evidenced by the mean and median slope of regression lines fitted to the sequence of position fixes captured during each visit to a control point (Table 2). This implies that the first hypothesis cannot be rejected, however other results should also be considered. For example, in Table 2 one can see that the Croat. j. for. eng. 33(2012)1

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Table 2 Average regression-related information from 50 position fixes collected per visit to three forest types on the Whitehall Forest GPS Test Site (Georgia, USA) Tablica 2. Prosje~ni regresijski podaci za 50 polo`ajnih ~vrstih to~aka prikupljenih po snimanju u razli~itim tipovima {uma na istra`ivanom podru~ju – Whitehall (Georgia, SAD) Mean Srednja vrijednost

Slope, b1 – Nagib, b1 Coefficient of Determination R2 Vrijednost koeficijenta odre|ivanja, R2 Slope, b1 – Nagib, b1 Coefficient of Determination, R2 Vrijednost koeficijenta odre|ivanja, R2 Slope, b1 – Nagib, b1 Coefficient of Determination, R2 Vrijednost koeficijenta odre|ivanja, R2

–0.020 0.595 –0.003

Median Medijana

Minimum Minimalna

Maximum Maksimalna

vrijednost

Young coniferous – Mlada {uma ~etinja~a –0.011 –0.588 0.700

0.000

Older coniferous – Starija {uma ~etinja~a –0.006 –0.300

Percent of days within one standard deviation of the mean Postotak dana unutar standardne devijacije srednje vrijednosti

0.297

0.893

0.332

0.546

0.640

0.000

0.938

0.003

Deciduous – [uma lista~a –0.008 –0.250

0.562

0.548

0.674

0.917

minimum and maximum slope values for regression lines developed on individual visits can be either positive (indicating a reduction in accuracy as the number of position fixes captured increases) or negative (indicating an increase in accuracy as the

0.000

number of position fixes captured increases). Fig. 3 illustrates two cases with high coefficient of determination (R2) values that suggest either of these trends may be observed. Further, while the R2 values of the regression lines fit to the fifty position fixes from

Fig. 3 RMSE values for fifty consecutive position fixes collected at a control point in the young coniferous forest, and regression lines drawn to describe changes ((a) improvement and (b) decline) in static horizontal position accuracy Slika 3. Vrijednosti srednje kvadratne pogre{ke za pedeset uzastopnih ~vrstih to~aka prikupljenih na kontrolnoj to~ki u mladoj {umi ~etinja~a i regresijske krivulje povu~ene kako bi prikazale promjene ((a) pobolj{anja i (b) pogor{anja) to~nosti stati~koga horizontalnoga polo`aja Croat. j. for. eng. 33(2012)1

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Table 3 Difference in RMSE (m) from one position fix collected to an average of X position fixes (up to 50, in steps of 10) collected per visit to three forest types on the Whitehall Forest GPS Test Site (Georgia, USA) Tablica 3. Razlika u srednjoj kvadratnoj pogre{ci (m) od jedne poloàjne ~vrste to~ke do prosje~ne vrijednosti za X poloàjnih ~vrstih to~aka (do 50, u koracima po 10) prikupljenim po jednom snimanju unutar razli~itih tipova {uma istraìvanoga podru~ja Whitehall (Georgia, SAD) Difference between one position fix collected and X position fixes, m – Razlika izme|u jedne poloàjne ~vrste to~ke i X poloàjnih ~vrstih to~aka, m Forest type – Vrsta {ume X = 10 X = 20 X = 30 X = 40 X = 50 Young coniferous – Mlada {uma ~etinja~a –0.126 –0.252 –0.381 –0.477 –0.568 Older coniferous – Starija {uma ~etinja~a 0.008 0.002 –0.024 –0.034 –0.053 Deciduous – [uma lista~a 0.031 0.110 0.160 0.193 0.184 each visit ranged from 0.55 to 0.70 on average, some visits produced highly linear trends (R2 > 0.90), while some visits did not show any trend (R2 = 0.00). However, the percentage of days with regression slope values that were within one standard deviation of the mean was very high for all three forest types (Table 2). In the young coniferous forest, only 5.4% of the regression slope values were below one standard deviation from the mean, and only 2.3% were one standard deviation above the mean. In the older coniferous forest, only 3.4% of the regression slope values were below one standard deviation from the mean, and only 5.0% were one standard deviation above the mean. And in the deciduous forest, only 2.0% of the regression slope values were one standard deviation below the mean, while only 7.4% were one standard deviation above the mean. Further, in the young coniferous forest, the trend during the spring season (a slight increase in static horizontal position accuracy with increases in numbers of position fixes) was significantly different (p < 0.05) than the trends observed in the other seasons of the year. No other significant differences among the seasons were observed with regard to the young coniferous forest. No significant differences (p < 0.05) among the seasons were observed with regard to the older coniferous forest and the deciduous forest. So while it seems that static horizontal positional accuracy does not significantly change with an increasing number of position fixes used to determine a position’s location (leading to a decision not to reject H1), the results are not entirely conclusive, and the season of year may influence results for some forest types (e.g., young coniferous forests), where there is a relatively high density of trees per unit area that are also relatively short. Due to the high level of variation among RMSE values observed each day, statistical tests designed to examine the difference between the first position fix RMSE and an average RMSE of a larger set of position fixes all show no significant differences among the mean values. However, if one were to simply examine the difference in static horizontal position

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accuracy (as represented by RMSE values) between the first and an average of a larger set, trends do emerge (Table 3). Through this analysis, we find that the difference in RMSE between the first position fix and an average of fifty position fixes is over 0.5 m in the young coniferous forest, which suggests that a larger set (at least 40 or 50) of position fixes would be necessary in the young coniferous forest to better describe a static horizontal position. In examining the results related to the older coniferous forest, we find very little difference, on average, between the first position fix collected and the average of larger sets of position fixes. In this case, where trees are taller and the forest is less dense, a static horizontal position could be estimated just as accurately with one position fix as with a larger set of position fixes (using the receiver tested in this research, of course). In the older deciduous forest we found that static horizontal position accuracy tended to decrease slightly, to about 0.2 m worse after averaging fifty position fixes. Therefore, as with the older coniferous forest, a static horizontal position could be estimated just as accurately with one position fix as with a larger set. Given these observations, we suggest rejecting the second hypothesis, which proposed that the trends do not differ by forest type or by density of trees per unit area.

4. Discussion –Rasprava In previously published research involving the data used here (Bettinger and Fei 2010), we found that static horizontal position accuracy was significantly different in deciduous, older coniferous, and younger coniferous forests, regardless of the season. The consumer-grade receiver that was tested determined static horizontal positions that were consistent with other similar devices tested in the same area, and however it was observed that trends in individual position fix values were evident during visits to the control points. Therefore, this analysis was conducted in order to delve into the trends that Croat. j. for. eng. 33(2012)1

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were observed during individual visits to control points in three types of forests in the southern United States. When using low-cost consumer-grade GNSS receivers, fifty position fixes seems to be the most one would need to determine a horizontal position. In fact, in some cases (older, less dense forests), one position fix may return an estimated position that would be just as accurate as the average of a larger set. However, we have shown that younger and more dense coniferous forests (with shorter trees) may require an average of 40 – 50 position fixes to better describe the horizontal position, if an improvement of 0.5 m of accuracy were important. These suggestions are for management applications, of course. When studying the effects of terrain, vegetation, and weather on the accuracy of positions determined by a GNSS receiver, one would want to collect at least fifty position fixes given the variability that can be observed within a 2 – 3 minute span of time. One obvious limitation of this work is that a single GNSS receiver was studied, and it was a relatively low-cost device (around $ 400 USD). Unfortunately, time and funding constraints influenced the protocols developed for the study. We acknowledge that an assessment of a larger set of GNSS receivers in the manner described here would provide further evidence of trends in position fix accuracy. The more troubling aspect of this enhancement is the time required to perform a long-term study. For the work presented here, 20 minutes per day were required for field data collection purposes. With each additional receiver or each change in parameter setting, 20 more minutes would be required per day. We are not implying that this type of research is impossible to conduct, however, receiver manufacturers and government agencies seem reluctant to invest in these types of forestry studies. In our case, the research was unfunded, therefore while improvements to the study design were considered, given time constraints, many were not pursued.

5. Conclusions – Zaklju~ci In an assessment of the changes in static horizontal position accuracy of a single low-cost, consumer-grade GNSS receiver, we failed to reject a hypothesis that static horizontal position accuracy does not significantly change with increasing numbers of position fixes collected. However, we favor rejecting the hypothesis that trends do not differ by forest type or by density of trees per unit area. Therefore, we suggest that when using a GNSS receiver similar to the one we studied, static horizontal positional accuracy does not significantly change with an increasCroat. j. for. eng. 33(2012)1

P. Bettinger and K. Merry

ing number of position fixes used to determine a position’s location (leading to a decision not to reject H1). However, the results are not entirely conclusive, and the season of the year may influence results for certain forest types (e.g., young coniferous forests). Daily visit trends in the improvement (or decline) of static horizontal position accuracy for three forest types were observed over the long-term study. We found that the static horizontal position accuracy in the young coniferous forest, on average, improved from that determined by a single position fix to that determined by a set of fifty position fixes. A much more minor decline in accuracy was noted in the deciduous forest, and no trend was observed in the older coniferous forest.

Acknowledgements – Zahvala We appreciate and value the thoughtful concerns of the anonymous reviewers of this manuscript.

6. Reference – Literatura Andersen, H. E., Clarkin, T., Winterberger, K., Strunk, J., 2009: An accuracy assessment of positions obtained using survey-grade and recreational-grade Global Positioning System receivers across a range of forest conditions within the Tanana Valley of Interior Alaska. Western Journal of Applied Forestry 24(3): 128–136. Bettinger, P., Fei, S., 2010: One year’s experience with a recreation-grade GPS receiver. International Journal of Mathematical and Computational Forestry & Natural-Resource Sciences 2(2): 153–160. Bolstad, P., Jenks, A., Berkin, J., Horne, K., Reading, W. H., 2005: A comparison of autonomous, WAAS, real-time, and post-processed Global Positioning Systems (GPS) accuracies in northern forests. Northern Journal of Applied Forestry 22(1): 5–11. Danskin, S. D., Bettinger, P., Jordan, T. R., 2009a. Multipath mitigation under forest canopies: A choke ring antenna solution. Forest Science 55(2): 109–116. Danskin, S. D., Bettinger, P., Jordan, T. R., Cieszewski, C., 2009b: A comparison of GPS performance in a southern hardwood forest: Exploring low-cost solutions for forestry applications. Southern Journal of Applied Forestry 33(1): 9–16. Hasegawa, H., Yoshimura, T., 2003: Application of dual-frequency GPS receivers for static surveying under tree canopies. Journal of Forest Research 8(2): 103–110. Keskín, M., Say, S. M., Keskín, S. G., 2009: Evaluation of a low-cost GPS receiver for precision agriculture use in Adana Province of Turkey. Turkish Journal of Agriculture and Forestry 33(1): 79–88.

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Klimánek, M., 2010: Analysis of the accuracy of GPS Trimble JUNO ST measurement in the conditions of forest canopy. Journal of Forest Science 56(2): 84–91.

Sigrist, P., Coppin, P., Hermy, M., 1999: Impact of forest canopy on quality and accuracy of GPS measurements. International Journal of Remote Sensing 20(18): 3595–3610.

Naesset, E., Gjevestad, J. G., 2008: Performance of GPS precise point positioning under conifer forest canopies. Photogrammetric Engineering & Remote Sensing 74(5): 661–668.

Wing, M. G., 2008: Consumer-grade Global Positioning Systems (GPS) receiver performance. Journal of Forestry 106(4): 185–190.

Pirti, A., 2005: Using GPS near the forest and quality control. Survey Review 38(298): 286–299. Pirti, A., 2008: Accuracy analysis of GPS positioning near the forest environment. Croatian Journal of Forest Engineering. 29(2): 189–199. Pirti, A., Gümüs, K., Erkaya, H., Hosbas, R. G. 2010: Evaluating repeatability of RTK GPS/GLONASS near/under forest environment. Croatian Journal of Forest Engineering 31(1): 23–33. Ransom, M. D., Rhynold, J., Bettinger, P., 2010: Performance of mapping-grade GPS receivers in southeastern forest conditions. RURALS: Review of Undergraduate Research in Agricultural and Life Sciences 5(1): Article 2, 14 p.

Wing, M. G., 2009: Consumer-grade Global Positioning Systems performance in an urban forest setting. Journal of Forestry 107(6): 307–312. Wing, M. G., Eklund, A., Sessions, J., Karsky, R., 2008: Horizontal measurement performance of five mapping-grade Global Positioning System receiver configurations in several forested settings. Western Journal of Applied Forestry 23(3): 166–171. Wing, M. G., Karsky, R., 2006: Standard and real-time accuracy and reliability of a mapping-grade GPS in a coniferous western Oregon forest. Western Journal of Applied Forestry 21(4): 222–227. Yoshimura, T., Hasegawa, H., 2003: Comparing the precision and accuracy of GPS positioning in forested areas. Journal of Forest Research 8(3): 147–152.

Sa`etak

Stati~ke horizontalne pozicije odre|ene prijemnikom GNSS (korisni~ke vrste): procjena broja potrebnih ~vrstih to~aka Ciljevi su ovoga rada sadr`ani u utvr|ivanju mijenjanja to~nosti stati~koga horizontalnoga polo`aja s obzirom na broj ~vrstih to~aka prikupljenih tijekom snimanja na poznatoj kontrolnoj to~ki. Hipoteze su sljede}e:

H1: To~nost stati~koga horizontalnoga poloàja ne mijenja se zna~ajno s pove}anjem broja ~vrstih to~aka kori{tenih za odre|ivanje poloàja. H2: Kretanja se to~nosti stati~koga horizontalnoga poloàja, s porastom broja ~vrstih to~aka, ne razlikuju s obzirom na tip {ume ili gusto}u stabala. Izme|u rujna 2008. i rujna 2009. godine pomo}u GPS prijamnika Garmin Oregon 300 gotovo svakoga dana prikupljani su podaci u raznolikim stani{nim uvjetima. Stati~ki horizontalni poloàji snimani su GPS-om u mladoj {umi ~etinja~a (Pinus taeda), u starijoj {umi ~etinja~a te u {umi lista~a na lokaciji ispitnoga podru~ja Whitehall Forest, Athens, GA (Atena, Georgia, SAD). Prosje~ni stati~ki horizontalni poloàji iznosili su 11,9 m, 6,6 m, i 7,9 m za mladu {umu ~etinja~a, stariju {umu ~etinja~a, odnosno bjelogori~nu {umu. Tri su kontrolne to~ke (brojevi 6, 31, 37) odabrane za ovo istraìvanje izme|u raspoloìvih na istraìvanom podru~ju Whitehall (slika 1). Kontrolna to~ka 37 smje{tena je u mladoj borovoj {umi (slika 2), a sastojinski ~imbenici u vrijeme istraìvanja prikazani su u tablici 1. Kontrolna to~ka 31 smje{tena je u starijoj {umi ~etinja~a, a kontrolna to~ka 6 u {umi lista~a. Sve tri kontrolne to~ke smje{tene su na povi{enim mjestima (upper slope positions) u odnosu na okolno podru~je te predstavljaju najbolji izbor za usporedbu izme|u tih triju tipova {ume. To~ke su obilaène jednom dnevno tijekom godine, raspored posjeta bio je u potpunosti nasumi~an i svaki je put prikupljeno pedeset ~vrstih poloàjnih to~aka. Nadalje, po{lo se pretpostavkom kori{tenja samo jednoga prijamnika GNSS koji bi imao nepromjenjive radne parametre tijekom cijele studije kako bi se koristili sli~ni uvjeti prikupljanja podataka. Snimljeni (neobra|eni) podaci, koji predstavljaju srednju kvadratnu pogre{ku svake odre|ene ~vrste poloàjne to~ke, izjedna~eni su linearnom regresijom ~ime se odredio nagib i koeficijent odre|ivanja (R2) linije, a ona najbolje

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odgovara uklapanju unutar pedeset ~vrstih to~aka svakoga pojedinoga dana snimanja na kontrolnom poloàju. Analiza je vo|ena tijekom svih 298 dana istraìvanja i za svaki od triju tipova {ume. U tim slu~ajevima jednostavne linearne regresije nezavisna je varijabla srednja kvadratna pogre{ka svake ~vrste to~ke, a zavisna je varijabla broj ~vrstih to~aka (1 do 50). Za potrebe prikazivanja uprosje~ene su vrijednosti nagiba i koeficijenta odre|ivanja kako bi se moglo zaklju~iti prihva}a li se prva hipoteza, pri ~emu se to~nost stati~koga horizontalnoga poloàja ne mijenja zna~ajno s pove}anjem broja poloàjnih ~vrstih to~aka kori{tenih za odre|ivanje stvarnoga poloàja. S obzirom na mno{tvo od pedeset ~vrstih to~aka prikupljenih prilikom svakoga mjerenja na pojedinoj kontrolnoj to~ki, ti su podaci smanjeni na {est procjena srednje kvadratne pogre{ke: (1) prva ~vrsta to~ka, (2) srednja vrijednost prvih deset ~vrstih to~aka, (3) srednja vrijednost prvih dvadeset ~vrstih to~aka, (4) srednja vrijednost prvih trideset ~vrstih to~aka, (5) srednja vrijednost prvih ~etrdeset ~vrstih to~aka, (6) srednja vrijednost svih pedeset prikupljenih ~vrstih to~aka. Kako bi bilo jasnije, srednja je kvadratna pogre{ka odre|ena za svaku poloàjnu ~vrstu to~ku, a potom su vrijednosti pogre{aka uprosje~ene u grupnu prosje~nu stati~ku horizontalnu pogre{ku. Budu}i da je postojala velika koli~ina varijacija u vrijednostima srednje kvadratne pogre{ke od dana do dana, u analizi je kori{tena razlika vrijednosti izme|u srednje kvadratne pogre{ke prve ~vrste to~ke i prosje~ne kvadratne pogre{ke ostalih pet skupina. Ova je analiza osmi{ljena za rje{avanje druge hipoteze, koja je sugerirala kako se rezultati mogu razlikovati s obzirom na vrstu {ume i obrast. Na temelju svega navedenoga izvedeni su ovi zaklju~ci: pri kori{tenju prijamnika GNSS tipa nièga cjenovnoga razreda to~nost stati~koga horizontalnoga poloàja ne mijenja se zna~ajno s pove}anjem broja ~vrstih to~aka kori{tenih za odre|ivanje lokacije poloàja ({to vodi do zaklju~ka da se hipoteza H1 ne odbacuje). Me|utim, rezultati nisu u potpunosti pouzdani jer i godi{nje doba moè utjecati na rezultate u pojedinim tipovima {uma (mlada {uma ~etinja~a). Kretanja dnevnih snimanja u pobolj{anju (ili pogor{anju) to~nosti stati~koga horizontalnoga poloàja za tri tipa {uma promatrana su kroz dugotrajnu studiju. Utvr|eno je da se to~nost stati~koga horizontalnoga poloàja u mladoj {umi ~etinja~a u prosjeku pobolj{ala od one odre|ene jednom ~vrstom to~kom do one odre|ene pomo}u pedeset ~vrstih to~aka. Mnogo manji pad to~nosti utvr|en je u listopadnoj {umi, dok nikakva kretanja to~nosti nisu otkrivena u starijoj {umi ~etinja~a. Klju~ne rije~i: globalni navigacijski satelitski sustavi, to~nost stati~koga horizontalnoga poloàja, srednja kvadratna pogre{ka, linearna regresija

Authors’ address – Adresa autorâ:

Received (Primljeno): March 07, 2011 Accepted (Prihva}eno): October 01, 2011 Croat. j. for. eng. 33(2012)1

Prof. Pete Bettinger, PhD. e-mail: pbettinger@warnell.uga.edu Krista Merry Research Professional e-mail: kmerry@warnell.uga.edu University of Georgia School of Forestry and Natural Resources 180 E. Green Street Athens, GA 30602 USA

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Subject review – Pregledni rad

Opening-up of Forests for Fire Extinguishing Purposes Andrea Majlingová Abstract – Nacrtak Information on the existence of forest roads as well as their quality is important not only for planning forest management activities, but also for fire management, which includes fire risk assessment and fire suppression. In the case of fire, the level of forest opening-up has a significant influence on the attendance time of fire brigades. Not sufficiently developed road network is often reflected on the elongation of fire-fighting attack and exactingness of shuttle water relay. Therefore, the level of forest opening-up is an important indicator and factor affecting the promptness of fire-fighting activities and further fire spreading, because forest roads also represent a natural barrier against fire. A simple approach to the assessment of the level of forest opening-up has been introduced from the aspect of terrain accessibility for the available mobile fire apparatus with the use of GIS and GNSS technologies. First, the forest road network was mapped using the GNSS technology, and then the information on the quality of particular roads was collected. These data were processed in the ArcGIS 9.3 environment and as a result the geodatabase was created. It was later used to process the opening-up analysis in IDRISI Taiga environment. The opening-up analysis was performed for the Hrabusice forest management district, located in the karst area of the Slovensky raj National Park and the available mobile fire apparatus – pumping appliance CAS 32 on Tatra 148 chassis and forest special UNIMOG on Mercedes chassis. The objective of the opening-up analysis was to identify the zone where the terrain is accessible for mobile fire apparatus and where fire hose piping is admissible. It was based on computation of the maximum range of fire hose piping (maximum sidelong distance), road spacing and the index of forest opening-up. The results of this analysis are valuable as a support for decision making for foresters dealing with forest protection, road planning and construction, for fire brigades in planning fire attacks, as well as for risk managers and crisis managers. Keywords: Fire extinguishing, forest fire, GIS, GNSS, opening-up

1. Introduction – Uvod The intensive exploitation of natural resources gives rise to significant claims of forest management oriented not only to sustaining and improving of wood production functions of forest, but also towards its non-production functions, such as soil protection, hydrological control, landscape architecture, health and recreation. Forest fires are among the most harmful factors in forestry representing the highest risk for fulfilling the objectives of forest management planning. Croat. j. for. eng. 33(2012)1

In the period 2000–2010, there occurred 4 373 forest fires in Slovakia that destroyed about 5 831 ha of forests (JRC Scientific and Technical Report 2010). This is the reason to incorporate the effective fire protection system into a system of multi-resource forest management. The most effective fire protection is effective prevention, and if, however, a fire occurs, it is necessary to establish promptly its location and provide extinction. The functional and efficient network of forest roads is a basic pre-requisite for a sustainable multi-resource forest management as well as for fire protection.

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Opening-up of Forests for Fire Extinguishing Purposes (159–168)

In steep mountainous terrain, where the use of ground-fire-fighting machinery (mobile fire apparatus) is required, the operational facilities of this machinery (mainly its working range) as well as the access to the fire place are the limiting factors (Chromek 2006). In Slovakia, 3 types of mobile fire apparatus are commonly used: pumping appliance CAS on Tatra 148 and Tatra 815 chassis and forest special UNIMOG on Renault or Mercedes chassis. The pumping appliance is suitable for extinguishing fires on public roads of 1st and 2nd quality class and on reinforced forest roads (in Slovakia 1L, 2L class forest roads in accordance with STN 73 6108). Due to its technical parameters, the UNIMOG is also suitable for extinguishing fires on hauling roads (with the longitudinal slope from 10 to 12%). This paper deals with the assessment of opening-up of the area of Hrabusice forest management district for the purposes of extinguishing fires with the use of mobile fire apparatus: pumping appliance CAS 32 on Tatra 148 chassis and forest special UNIMOG on Mercedes chassis. The choice of fire apparatus was not oriented to the latest and most powerful machine, but to the model actually used by fire brigades acting in this territory.

2. Problem – Problem Effective forest fire prevention is a pre-requisite for good forest management in fire prone areas. To have a sufficiently developed road network of good quality that can be used for efficient fire-fighting is a sign of well-done fire prevention that can lead to reduction of fire vulnerability in that territory. Planning of forest roads is commonly oriented to assigning the fundamental management activities in the forest and to reducing the costs and environmental impacts of timber logging. Nowadays, the analyses of forest opening-up are performed mainly as a part of timber logging process optimization. For this purpose the computer aided or GIS approaches are used. Numerous authors have been concerned with these problems for many years. Tan (1999) was interested in locating forest roads by a spatial and heuristic procedure using microcomputers. Tu~ek and Pacola (1999) introduced the algorithms for tractor and cableway skidding distance modelling on a raster digital terrain model in GIS environment. Adams et al. (2003) published an approach to the modelling of steep terrain harvesting risk using GIS.

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Eriksson and Rönnqvist (2003) presented a decision support system for transportation and route planning in Sweden as well as the Akarweb – web based planning system. Andreson and Nelson (2004) published an optimization approach to the projecting vector-based road network based on the shortest path algorithm applicable in GIS environment. Gumus at al. (2007) introduced a new network planning approach developed for wood-harvesting. GIS was also used for data evaluation and planning process. It was applied to Catak Forest District area. Contreras and Chung (2007) published in their work a computer approach to finding optimal long landing location and analyzing influencing factors for ground-based timber harvesting. Slan~ík at al. (2009) introduced the model for optimization of timber logging and transportation technologies regarding the ecological criteria. It was created using GIS and EMDS tools. In 2010, Kühmaier and Stampfer introduced a GIS based evaluation model designed to select the optimal timber harvesting system. The model has been demonstrated in steep terrain in the South of Lower Austria. The requirements related to fire extinguishing activities in the forest are not well implemented into to forest management planning. However, there are few works dealing with the problem of opening-up analyses as a simultaneous combination of requirements related to forest management and fire risk management. Johnsson at al. (1998) published a scientific paper dealing with the problem of integration of wildfire into strategic planning for Sierra Nevada forests. Gonzáles at al. (2005) dealt with the problem of integrating fire risk in forest management planning on landscape-level perspective in Spain. Acuna at al. (2010) introduced an approach to the integrated spatial fire and forest management planning. They applied it in the boreal forest region of the province of Alberta in western Canada. In Slovakia, there are also activities related to the planning and reconstruction of fire protection roads, e.g. Dvor{~ák and Bohmer (2006); Antalová (2010), or fire stop systems (Hlavá~ at al. 2007). In our conditions only B`hmer and Dvor{~ák (2006) dealt with the problem of optimization of forest opening-up for the purpose of fire extinguishing. In the optimization process they considered a pumping appliance »CAS 32« and a portable pump »PS 12«. The analysis was performed by the classic mathematical approach. In the calculation they also Croat. j. for. eng. 33(2012)1

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included the friction losses because of different terrain slope. The implementation of GIS methods into the analysis allows performing parallel processing of several inputs resulting in increasing time and cost efficiency in sense of reduction of exerted work, time saving and reduction of errors caused by a subjective view on the analyzed phenomenon.

3. Material and methodology – Materijal i metodologija 3.1 Experimental area – Podru~je istra`ivanja On the basis of the results of fire danger assessment of the forests of the Slovak Republic (Majlingová 2007), the territory of Slovensky raj National Park, and hence also Hrabusice management district, is the region with the highest degree of fire danger in Slovakia. This is mainly so because of the climate conditions, forest species composition, inaccessible terrain – very low level of forest opening-up, number of tourists and people living in poverty (Majlingová 2010). The Slovensky raj National Park is situated in the north-eastern part of the Slovenske Rudohorie Mts. near the Low Tatras Mts. Fig. 1 shows the location of the experimental area. The geological ground consists of limestone and dolomite that allow the creation of karst formations. The predominant soil types are rendzinas, pararendzinas and lithosols (80 – 90% of the area). Forest covers about 75% of the area. The most represented tree species is spruce (50%), fol-

Andrea Majlingová

lowed by beech (30%). The climate characteristics show that the preponderance of the area belongs to a moderately cold region with an average annual temperature of 5 – 6 °C. Climate conditions together with the meteorological situation represent significant factors for fire initiation. The highest fire danger periods are the spring season (March – May) and the summer season, with the months with the highest air temperature (July and August). This region is well-known for an abundance of canyons, ravines, caves. It is also well known because of well-developed tourism. Every year more than 300 000 visitors come here. For fire extinguishing purposes in the experimental area, two types of mobile fire apparatus are commonly used: the pumping appliance »CAS 32« on Tatra 815 chassis and special forest mobile apparatus called »UNIMOG« on Mercedes chassis.

3.2 Basic technical parameters of the mobile fire apparatus – Osnovni tehni~ki parametri kori{tene vatrogasne opreme CAS 32 Tatra 148 has an excellent driveability and quantity of extinguishing substances (6000 l). It is most commonly used in fires in inaccessible terrain (forest fires, old grasslands, etc.). Pump power output is 3200 lmin–1 at a pressure of 0.8 Mpa. It is used to transport members of the fire brigade (1 + 2) and material as well as pressure, foaming, assistance and rescue equipment. Mercedes–Benz UNIMOG is primarily used in the transport of extinguishing agents (2500 litres of water and 150 litres of foam) as well as members of

Fig. 1 Location of the experimental area Slika 1. Lokacija istra`ivanoga podru~ja Croat. j. for. eng. 33(2012)1

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the fire brigade (1 + 2) and material together with the pressure, foaming, assistance and rescue equipment. This vehicle is suitable to be applied in a harsh and inaccessible terrain non-passable for another fire machine. The technical equipment of both types of apparatus, designed to ground attack, is generally composed of 2 hoses with the diameter of 75 mm (»B« type) and the length of 20 m, 2 hoses with the diameter of 75 mm and the length of 5 m and 5 hoses with the diameter of 54 mm and the length of 20 m. Therefore the total length of the delivery fire hose piping could be up to 150 m (it is also the maximum range value).

3.3 Methodology of data collection and pre-processing in ArcGIS environment Metodologija prikupljanja podataka i obrada u ArcGIS-u In the pre-processing phase, vector layer of the actual forest road network was obtained using the

position measurement with the Trimble GeoXH GNSS device as well as information about its current condition obtained by terrain survey. Both sources were used to create the geodatabase that was later used in the opening-up analysis. The position and attributes of forest road network were then corrected on the basis of the orthophotos in ArcGIS environment. The corrections were done manually by editing the position errors. Pieces of information on the road owner/user, road category, road and hauling road cover were entered into the database and changes related to specific sections of forest road network were proposed.

3.4 Methodology of forest opening-up analysis in IDRISI Taiga environment – Analiza otvaranja {uma primjenom softverskoga paketa IDRISI Taiga The analysis of forest opening-up was performed in IDRISI Taiga environment using the functions of context operators, map algebra and distance analyses.

Fig. 2 Development diagram of the forest opening-up analysis Slika 2. Dijagram razvoja algoritma za analizu otvaranja {uma 162

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Due to the variability of conditions related to water relay and the direction of extinguishing (upslope or downslope), both directions of fire extinguishing were taken into consideration in the calculation. Based on the calculated maximum range values of the delivery of fire hose piping, the road spacing was calculated using the formula published in B`hmer and Dvor{~ák (2006). The calculated maximum range of delivery of fire hose piping also determines the zone where mobile fire apparatus can be applied for fire extinguishing. The following data were used as the input layers to the opening-up analysis: digital relief model with the spatial resolution of 10 m, vector layer of forest unit borders and vector layer of road network representing the actual situation in spatial distribution of forest roads in the experimental area, obtained by road network mapping using the GNSS technology. The resulting values of the analysis of forest opening-up and extraction for individual forest stands are shown in the development diagram (Fig. 2). The first step was the data pre-processing. The digital relief model was used as a source for the slope raster calculation – module SURFACE. It was calculated in percentage. For the purposes of further analysis it was consecutively converted to the radians – module TRANSFORM. The vector representation of forest roads, distributed in the experimental area, was also converted to the raster representation (module RECLASS) – binary raster (1 – roads suitable to be used by the mobile fire apparatus, 0 – the other roads). The next step was to calculate the cell sloping distances using map algebra tools (module Image Calculator). The input raster for this calculation was the raster of slope converted to the radians. The calculation was performed based on the formula: dslope = 10/cos a

(1)

Where: dslope sloping distance, m 10 resolution of the raster cell, m a angle which contains the hypotenuse with an adjacent leg (or raster of slope in GIS), ° The output raster was used as a friction surface raster for the calculation of cost distances, using distance operators – module COSTGROW. In the calculation it had been considered with 2 types of analyses. The first was performed for the pumping appliance CAS 32 used for extinguishing fires from reinforced forest roads and the other for the UNIMOG which uses skidding roads except the reinforced ones. Croat. j. for. eng. 33(2012)1

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The next step was to calculate the horizontal lengths of the fire hose piping and road spacing. Providing that the road spacing is considered as the distance of its orthographic projections into the horizontal level, it was necessary to recalculate the appropriate diagonal lengths of the fire hose line onto horizontal ones according to the following equation. For that purpose the Map algebra tools (module Image Calculator) were applied. s )) (2) dhoriz = dslope ´ cos (arctg ( 100 Where: dhoriz horizontal distance [m] (cost distance raster) dslope sloping distance, m s slope, ° The output raster was consecutively reduced (module RECLASS) to the zone of extinguishing using the mobile fire apparatus – the area opened up for ground fire extinguishing. The maximum range of extinguishing zone was determined to 150 m due to the maximum length of delivery fire hose piping. Road spacing was calculated from the maximum horizontal length projections of the fire hose piping for upslope and downslope ways of water transport based on the formula: R = 2 ´ dhoriz

(3)

Where: R

road spacing, m

Furthermore, range values of the fire hose piping (sloping length of fire hose piping) were established for specific forest units, using module EXTRACT as the functions of Database Query operators. At the end the area opening-up index [%] was calculated as the ratio between accessible area [ha]/non accessible area [ha] and the whole experimental area.

4. Results and discussion – Rezultati s raspravom The amount of damage caused by forest fires depends not only on the fire extent and price of wood destroyed, but much more on the consequential ecological and environmental losses. Fire extinguishing mostly depends on the area opening-up and terrain accessibility. Effective fire prevention in forest management is also based on the early fire observation, prompt fire call and especially on the terrain accessibility. In fighting forest fires, in addition to early fire call and warning, the accessibility

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of localities affected by the fire is a crucial factor, followed by the provision of fire-fighting machinery and application of fire protection means. In this regard, the forest fund in Slovakia is divided into three groups: inaccessible area, hardly accessible area and easily accessible area. To improve the accessibility of mobile fire appliances, it is necessary to ensure the systematic development of the forest road network with the parameters enabling the passage of mobile fire-fighting machinery. This should be ensured by legal entities and individuals owning and managing forests (B`hmer and Dvor{~ák 2006). In case of fire, the level of forest opening-up also has significant influence on the attendance time of fire brigades. Generally, the minimum time for a fire flaring is 10 minutes. In mountainous, indented areas, the forest roads are not suitable for the use of the mobile fire apparatus. This is mainly due to their quality and technical parameters and it is reflected on the elongation of fire-fighting attack and exactingness of shuttle water relay. Consequently, the forest opening-up level can be considered as an important indicator and factor affecting the promptness of fire fighting activities and further fire spreading, because forest roads represent a natural barrier against fire. Partial results were then introduced leading to the calculation of opening-up index that expresses the actual state of the experimental area accessibility for the selected mobile fire apparatus. In the calculation of the maximum length of fire hose piping, the side slope was taken into consideration, as it strongly affects the losses in fire hose piping according to the recommendation published by B`hmer and Dvor{~ák (2006). The maximum length (working range) of the delivery fire hose piping was determined as 150 m, also taking into consideration the length of its particular components (technical equipment of the apparatus). The total range of the fire extinguishing zone is, therefore, between 0 – 300 m, due to two directions of extinguishing. However, this only applies in localities where the slope is not steep and the terrain conditions allow the use of the fire hose piping up to 150 m length. This is possible only in lowlands. In the mountainous terrain, the sloping distance is shorter and losses in the fire hose piping increase. Then the road spacing value of 300 m represents only a theoretical range of fire extinguishing zone. However, for the geomorphological conditions of Slovakia, the optimum road spacing is generally about 400 – 600 m. Table 1 shows the values of maximum sloping distance established for the specific forest units in

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Table 1 Maximum sloping distance values by forest units Tablica 1. Maksimalne stvarne udaljenosti pristupa povr{ini po odjelima Forest unit No. Broj odjela 197 198 199 200 201 202 203 204 205 206 207 208 209 341 345 476 486

Maximum sloping distance, m Maksimalne stvarne udaljenosti pristupa povr{ini, m CAS UNIMOG 959 985 1653 1653 1686 1691 1512 1512 1954 1969 2182 2231 2481 2536 2846 2875 2887 2887 2486 2511 2718 2718 2925 2925 2808 2808 107 157 105 129 105 104 98 134

The results of the calculated sloping distance for the UNIMOG are presented in Fig. 3.

the area. They were calculated as the distance from the nearest road to the specific forest units. Only the maximum values are presented for the forest units (calculated as the distance from the road to the furthest part of a forest unit). It should be pointed out here that the methodology of sloping distance calculation processing in GIS environment could also be considered as the result of this paper. Fig. 4 presents the view on opened up forest area for the UNIMOG fire mobile apparatus. This result was produced based on the classification of forest units into categories: 1 – forest unit with the average sloping distance less or equal to 150 m and 0 – forest unit with the average sloping distance of more than 150 m. Only the forest units classified as Class 1 are suitable for fire extinguishing with the mobile fire apparatus. The results of opening-up analysis can be best expressed by the means of opening-up index, which shows the fact that in case of use of the CAS 32Tatra 148 the experimental area was only 26% opened-up. In case of use of the UNIMOG, the percentage rate only increased to 30.5%. Croat. j. for. eng. 33(2012)1

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Fig. 3 Visualization of the results of the sloping distance calculation for UNIMOG, m Slika 3. Grafi~ki prikaz rezultata izra~unatih stvarnih udaljenosti pristupa povr{ini za UNIMOG, m

Fig. 4 Visualization of the results of forest opening-up analysis for UNIMOG Slika 4. Prikaz analize otvaranja {uma za UNIMOG Croat. j. for. eng. 33(2012)1

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Table 2 Survey of current opening-up in the experimental area Tablica 2. Postoje}a pristupa~nost terena u istra`ivanom podru~ju CAS 32 UNIMOG Extent – Povr{ina, ha Relative rate – Relativni udio, % Extent – Povr{ina, ha Relative rate – Relativni udio, % Total area – Ukupno 5528.23 100 5528.23 100 Accessible area – Pristupa~no podru~je 1437.34 26 1686.11 30.05 Inaccessible area – Nepristupa~no podru~je 4090.89 74 3842.12 69.5

The present level of forest opening-up of the Hrabusice forest management district is shown in Table 2. The results presented here refer to the low level of the area opening-up. This is mainly caused by the geomorphohological conditions of the experimental area. This is one of the most significant reasons why this area is the region with the highest number of forest fires and with the largest extent of the area burnt. It also implies the need to apply the aerial attack in case of fire. However this technology is more expensive and does not allow keeping a continuous shuttle water relay at the fire site as the mobile fire apparatus does.

5. Conclusions – Zaklju~ci The Slovensky raj National Park is known for its steep terrain, and numerous karst forms as gulches, ravines and canyons. However, it is also well known because of the fire occurrence in the area. The forest fires that occurred in the past affected large areas and it took several days to extinguish them. Six people burnt during extinguishing a fire that occurred in this area in 2000. Therefore, mainly because of the high fire risk in this area, it is necessary to provide the opening-up of this area. Due to operational tactics, it is generally known that in the Slovensky raj National Park the aerial attacks were mainly used for extinguishing fires. The results presented in this paper confirm the need for their use based on the low level of the area opening-up. For this reason the mobile fire apparatus could only be used for fire extinguishing in areas that are properly opened up by reinforced forest roads of good quality. The advantage of the area opening-up analysis and evaluation method based on GIS is the fact that it allows processing of the analysis for any area in a relatively short time and at low costs, which allows efficient decision making on fire extinguishing tactics. The other advantage is GIS capability to also process and combine information about factors that could not be assessed in the terrain, e.g. because of smoke curtain.

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Acknowledgment – Zahvala This work was supported by the Grant Agency of the Ministry of Education, Science, Research and Sport of the Slovak Republic under the contracts No. VEGA 1/0714/10 andVEGA 1/0313/09.

6. Reference – Literatura Acuna, M. A., Palma, C. D., Cui, W., Martell, D. L., Weintraub, A. 2010: Integrated spatial fire and forest management planning. Canadian Journal of Forest Research 40(12): 2370–2383. Adams, J. D., Visser, R. J. M., Prisley, S. P., 2003: Modeling Steep Terrain Harvesting Risks using GIS. Proceedings of the second international precision forestry symposium. Seattle, Washington, 99–108. Anderson, A. E., Nelson, J., 2004: Projecting vector-based road networks with a shortest path algorithm. Canadian Journal of Forest Research 34(7): 1444–1457. Antalová, M., 2010: Projekt rekon{trukcie protipoìarnej lesnej cesty Tajchy In COYOUS 2010: konference mladých v deckých pracovníkç. Praha : êská zem d lská univerzita v Praze, 155–162. B`hmer, M., Dvor{~ák, P., 2006: Evaluation and optimization of fire control forest accessing for classic fire-fighting attack. Proceedings of the 2nd International Scientific Conference – Fire Engineering. Lu~enec, 35–44. Chromek, I., 2006: Vyuìtie leteckej techniky pri hasení lesných poìarov. Monography, Zvolen: Technická univerzita vo Zvolene, ISBN 80-228-1595-0. Contreras, M., Chung, W., 2007: A computer approach to finding an optimal log landing location and analyzing influencing factors for ground-based timber harvesting. Canadian Journal of Forest Research 37(2): 276–292. Eriksson, J., Rönnqvist, M., 2003: Decision support system/ tools: Transportation and route planning: Åkarweb – a web based planning system. Proceedings of the 2nd Forest Engineering Conference, Uppsala, Sweden, 48–57. Forest fires in Europe 2010: JRC Scientic and Technical Reports. Report Nb. 11. Joint Research Centre. Luxembourg: Publications Office of the European Union, European Union 2011. ISSN 1018-5593. Croat. j. for. eng. 33(2012)1

Opening-up of Forests for Fire Extinguishing Purposes (159–168) González, J. R., Palahí, M., Pukkala, T., 2005: Integrating fire risk considerations in forest management planning in Spain – A landscape level perspective. Landscape Ecology 20(8): 957–970. Gumus, S., Acar, H., Toksoy, D., 2007: Functional forest road network planning by consideration of environmental impact assessment for wood harvesting. Environmental Monitoring and Assessment 142(1–3): 109–116.

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ného seminára 8. setkání u `ivatelç Idrisi. MZLU Brno, 26–35. Majlingová, A., 2010: The methodological approach to the fire risk assessment of the natural environment. In Fire engineering proceedings. The 3rd international scientific conference, Technical University in Zvolen, Slovak Republic, 215–220.

Hlavá~, P., Chromek, I., Majlingová, A., 2007: Vybrané projekty protipo`iarnej ochrany lesa po vetrovej kalamite. Monography. Zvolen: Technická univerzita vo Zvolene.

Slan~ík, M., Suchomel, J., Lieskovský, M., Tu~ek, J., 2009: Modeling and optimization of timber logging and transportation technologies regarding the ecological criteria. In: Woodworking technique. Zalesina, Croatia, 257–265.

Johnson, K. N., Sessions, J., Franklin, J., Gabriel, J., 1998: Integrating wildfire into strategic planning for Sierra Nevada forests. Journal of Forestry 96(1): 42–49.

Tan, J., 1999: Locating forest roads by a spatial and heuristic procedure using microcomputers. International Journal of Forest Engineering 10(2): 91–100.

Kühmaier, M., Stampfer, K., 2010: Development of a multi-attribute spatial decision support system in selecting timber harvesting systems. Croatian Journal of Forest Engineering 32(2): 75–88.

Tu~ek, J., Pacola, E., 1999: Algorithms for skidding distance modeling on a raster digital terrain model. Journal of Forest Engineering 10(1): 67–79.

Majlingová, A., 2007: Analýza rizikových oblastí SR z hµadiska vzniku lesného po`iaru. Zborník referátov z odbor-

Sa`etak

Otvaranje {uma radi za{tite od poàra Podatak o koli~ini i prostornom razmje{taju {umske prometne infrastrukture vaàn je podatak ne samo za potrebe gospodarenja {umama ve} i za planiranje prevencije i za{tite {uma od poàra. U slu~aju {umskoga poàra podatak o prostornom razmje{taju {umske prometne infrastrukture ima velik utjecaj na vrijeme dolaska vatrogasne postrojbe na mjesto poàra. Nedovoljno razvijena mreà {umskih cesta ~esto se odraàva na produljenje protupoàrne obrane, a samim time i ve}e {tete nastale poàrom. Stoga je podatak o relativnoj otvorenosti {uma vaàn pokazatelj koji utje~e na brzinu protupoàrne za{tite i brzinu {irenja poàra jer je {umska prometna infrastruktura ujedno i prirodna barijera koja spre~ava {irenje poàra. [umski su poàri u Slova~koj najve}a prijetnja {umama i {umskomu zemlji{tu te su jedan od glavnih ~imbenika koji utje~u na (ne)ispunjavanje ciljeva zadanih osnovom gospodarenja. Od 2000. do 2010. godine zabiljeèna su 4373 {umska poàra u Slova~koj koji su opusto{ili oko 5831 ha {uma i {umskoga zemlji{ta (JRC Scientific and Technical Report 2010). Pri planiranju mreè {umske prometne infrastrukture do sada je naj~e{}e glavni cilj bio zadovoljiti zahtjeve gospodarenja {uma, a pri tome se najvi{e ra~una vodilo o smanjenju tro{kova pri sje~i i izradi te privla~enju drvnih sortimenata. Iz toga su razloga analize otvaranja {umskih podru~ja ra|ene uglavnom kao dio optimizacije pridobivanja drva, a zahtjevi vezani uz protupoàrnu za{titu donekle su uzimani u obzir ili uop}e nisu. U ovom je radu predstavljen jednostavan pristup odre|ivanja relativne otvorenosti {uma iz aspekta pristupa~nosti terena za dostupna vatrogasna vozila koriste}i tehnologiju GIS i GNSS. [umska prometna infrastruktura snimljena je pomo}u tehnologije GSNN te su tako dobiveni podaci o kvaliteti i u~inkovitosti {umskih cesta. U ra~unalnom programu ArcGIS 9.3 snimljeni podaci su obra|eni i kao rezultat napravljena je baza podataka koja je poslije kori{tena za analizu otvaranja istraìvanoga podru~ja u softverskom paketu IDRISIS Taiga uz primjenu funkcije algoritama, digitalne zemljovide i analize udaljenosti. Zbog varijabilnosti terenskih uvjeta i smjera ga{enja poàra u obzir i izra~un uzeta su oba smjera ga{enja poàra (uz nagib i niz nagib). Analiza otvaranja izvedena je za gospodarsku jedinicu »Hrabusice« koja ima najve}i indeks opasnosti od poàra u Slova~koj te je smje{tena u kr{kom podru~ju Nacionalnoga parka »Slovensky raj«. Indeks opasnosti od poàra za navedeno podru~je vrlo je velik zbog klimatskih uvjeta, sastava {umskih vrsta (udio smreke 50 %, bukve 30 % i ostale vrste 20 %), nepristupa~nosti terena (vrlo niske relativne otvorenosti), velikoga broja turista (godi{nje vi{e od Croat. j. for. eng. 33(2012)1

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Andrea Majlingová

Opening-up of Forests for Fire Extinguishing Purposes (159–168)

300 000 posjetitelja). Najve}a opasnost od {umskih poàra javlja se u prolje}e (oùjak – svibanj) te u ljetnim mjesecima za vrijeme najvi{ih temperaturnih vrijednosti (srpanj – kolovoz). Navedena je analiza napravljena za vatrogasna vozila Tarta 148 i Mercedesov Unimog opremljenih vatrogasnom opremom. Cilj je rada bio analizirati relativnu otvorenost istraìvanoga podru~ja te definirati nepristupa~na podru~ja za vatrogasna vozila Tarta 148 i Mercedesov Unimog opremljenih vatrogasnom opremom. Pristupa~nost podru~ja izra~unata je na temelju maksimalnoga dometa protupoàrnoga crijeva, udaljenosti izme|u {umskih cesta i indeksa otvaranja {uma. Efektivna za{tita od poàra u gospodarenju {umama temeljena je na ranom otkrivanju {umskih poàra, brzom dojavljivanju vatrogasnim postrojbama, pristupa~nosti terena i mogu}nosti kori{tenja razli~itih tehnika ga{enja poàra. [to se ti~e pristupa~nosti terena u Slova~koj, on je podijeljen u tri grupe: nepristupa~an, te{ko pristupa~an i lako pristupa~an teren. Da bi se pobolj{ala pristupa~nost terena kada se radi o {umskim poàrima, prijeko je potrebno osigurati planirani razvoj mreè {umske prometne infrastrukture koja }e mo}i podnijeti prometno optere}enje i omogu}iti nesmetan i siguran prolazak protupoàrnih kamiona. Najvi{a je duljina protupoàrnoga crijeva 150 m, uzimaju}i u obzir i duljinu pojedinih njegovih dijelova (tehni~ke opreme). Dakle, ukupni je raspon zone za ga{enje poàra izme|u 0 i 300 m, s obzirom na to da se gasiti moè u oba smjera. Takav na~in izra~una vrijedi samo za nizine (neznatan popre~ni nagib terena) gdje terenski uvjeti omogu}uju da raspon zone za ga{enje poàra iznosi 300 m. Na brdovitom i planinskom terenu zbog popre~nih nagiba terena i gubitaka u cjevovodu najvi{i raspon zone za ga{enje poàra od 300 m samo je teorijska vrijednost. Zbog toga i razmaci izme|u cesta od 300 m, na takvim podru~jima, nisu dostatni za potpunu za{titu. U Slova~koj optimalni razmak izme|u {umske prometne infrastrukture na brdskim i planinskim terenima iznosi izme|u 400 i 600 m. Ovim su radom dobivene vrijedne spoznaje kao potpora pri dono{enju odluka za za{titu {uma, pri planiranju novih {umskih prometnica te za vatrogasne postrojbe pri planiranju adekvatne i u~inkovite za{tite {uma od poàra. Klju~ne rije~i: ga{enje poàra, {umski poàr, GIS, GNSS, otvaranje {uma

Authors’ address – Autori~ina adresa:

Received (Primljeno): December 13, 2010 Accepted (Prihva}eno): March 28, 2011

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Andrea Majlingová, PhD. e-mail: amajling@vsld.tuzvo.sk Technical University in Zvolen Department of Fire Protection 24 T.G. Masaryka 960 53 Zvolen SLOVAKIA Croat. j. for. eng. 33(2012)1

ISSN 1845-5719

9 771845 571000